New update by theymos- https://bitcointalk.org/index.php?topic=5095156.0
It will be better if you check the update after understanding this thread.
Link to original- Marketplace trust

Earlier I made an explanation on how trust score is calculated. And requested LoyceV to add that one to his [GUIDES] on Bitcointalk. Index thread (until there is a dedicated subforum?).
A part of his reply-

Quote from: LoyceV on November 20, 2018, 01:04:32 PM

This reminded me an explanation of the DT-system is also needed.

And I am inspired to explain how DT System Works.

Senior people know how it works while newbie always gets confused. Sometimes, some senior member is also confused although it's quite simple. A lot of time people had replied with an answer on how DT system works. I have searched for a dedicated thread where OP has easily explained the DT system but didn't get one which is really friendly for the newbie.

So, let me write it easily so that newbie can understand it easily.

Before going to the explanation, I would like to discuss a little about feedback. In the forum, everyone can give a feedback on other member's profile. But, if you check someone's profile, not all of his/her feedback is shown on the profile page.
Let me give an example.
I have given negative feedback on Danydee's profile. If you check his profile, you will not see my feedback. Because I am not in your trust list. Now, include me on your trust list (Just for checking the feedback, later you may exclude). For including someone to your trust list,
Go to- Trust settings
You will see a blank space where only DefaultTrust is written, it's by default. Anyway, put my username there and click on update. Now, again visit Danydee's profile, you will see the negative feedback now.
By the way, those can also be seen by clicking on untrusted feedback on user's profile.

What is DT?
DT stands for DefaultTrust. Well, in fact, DefaultTrust is an account of the forum managed by admin. In your trust list, DefaultTrust is trusted by default. You can include/exclude anyone from your trust list though.
So, we got what is DT 0, you can also say list of people whom you trust.

Now, if DefaultTrust includes you on his trust list, you will be DT-1 member. If any DT-1 member includes you in his trust list, you will be DT-2 member.
If theymos wants to include someone to DT-1 list, theymos includes that person in DefaultTrusts trust list.
Now, if DT-1 members include someone in his/her trust list, that person becomes DT-2. I have already used an example. Again, for example, a DT-1 member has included user X in his trust list, so he/she becomes DT-2 but if another two DT-1 members exclude X from his trust list, X will no longer be in DT-2.

Feedback
Since you are trusting DefaultTrust by default, you are trusting all the DT-1 ad DT-2 members by default. Its simple, if you trust your friend, and your friend trusts another guy, logically you are trusting that another guy.
But you can still exclude a member from your trust list. For example, you dont trust DT-1 member X, go to your trust setting. In the box write tilde (~) and the DT-1 member name whom you dont want to trust. Its like {~X}. Or, if you don't want to trust anyone, simple put ~ before DefaultTrust.
Now if user DT-1 member 'X' gives someone a feedback, you will not see it by default.

Summary:
In trust setting, all those are mentioned as below-
Depth 0, the list of people who are included in your trust list.
Depth 1, the list of people who are trusted by Depth 0.
Depth 2, the list of people are trusted by Depth 1.

It seems enough for understanding the DT system. If someone else is still missing, feel free to ask question.
Thank you.

I will add here some replies in which DT system have been explained.
https://bitcointalk.org/index.php?topic=5045457.msg46607635#msg46607635 by subSTRATA
https://bitcointalk.org/index.php?topic=1475857.msg16157135#msg16157135 by DarkStar_
https://bitcointalk.org/index.php?topic=1947120.msg19352236#msg19352236 by Vod

Quote from: SFR10 on November 21, 2018, 09:29:59 AM

You might want to consider including the following link as well:

Quote from: theymos on September 10, 2015, 10:30:30 PM

https://bitcointalk.org/trust.txt.xz

I made it so that'll update every Saturday at 02:52 UTC. -> is "trusts", and -/> is "excludes". Only people with at least 1 post are included. If someone has never touched their trust list, then their trust in DefaultTrust is not shown.

Update-

How to be DT1 member:

Quote from: theymos on January 09, 2019, 08:25:07 PM

To illustrate, this is how the current DT1 was arrived at:

Static part: calculated only periodically
Each number includes the previous criteria.

Quote

- If rank was determined solely using earned merit, then you must be of at least Member rank.
- You must have been online sometime within the last 3 days.

2431 members

Quote

- Your trust list must include at least 10 users, not including ~distrust entries.

100 members

Quote

- You must have posted sometime within the last 30 days.

90 members

Quote

- You must not be banned or manually blacklisted from selection.

90 members

Quote

- You must have at least 10 people directly trusting you each with an earned merit of at least 10, not including merit you sent yourself.

23 members

Quote

- You must have at least 1 person directly trusting you with an earned merit of at least 100, not including merit you sent yourself.

23 members, giving a final DT1 of:

Code:

theymos
HostFat
dooglus
gmaxwell
OgNasty
SebastianJu
qwk
Cyrus
monkeynuts
TMAN
Lauda
Mitchell
Blazed
greenplastic
suchmoon
achow101
owlcatz
JohnUser
BitcoinPenny
zazarb
actmyname
The Pharmacist
krogothmanhattan

Dynamic part: recalculated constantly
(Omitting lists for undisputed ones.)

theymos: Total votes 9 = included
HostFat: Trusted by theymos; distrusted by gmaxwell, TMAN, Lauda, achow101, owlcatz, The Pharmacist. Total votes -6 = excluded.
dooglus: Total votes 8 = included
gmaxwell: Trusted by theymos, OgNasty, Cyrus, TMAN, Lauda, achow101, The Pharmacist; distrusted by HostFat. Total votes 6 = included.
OgNasty: Trusted by theymos, SebastianJu, greenplastic, achow101, krogothmanhattan; distrusted by TMAN, Lauda, suchmoon, owlcatz, BitcoinPenny, The Pharmacist. Total votes -1 = excluded
SebastianJu: Total votes 4 = included.
qwk: Total votes 5 = included
Cyrus: Total votes 7 = included.
monkeynuts: Total votes 6 = included.
TMAN: Trusted by Lauda, greenplastic, owlcatz, BitcoinPenny, The Pharmacist, krogothmanhattan; distrusted by OgNasty. Total votes 5 = included.
Lauda: Trusted by gmaxwell, qwk, TMAN, Blazed, suchmoon, owlcatz, JohnUser, BitcoinPenny, The Pharmacist; distrusted by HostFat, OgNasty. Total votes 7 = included.
Mitchell: Total votes 9 = included.
Blazed: Trusted by Cyrus, monkeynuts, TMAN, Lauda, Mitchell, suchmoon, BitcoinPenny, The Pharmacist, krogothmanhattan; distrusted by zazarb. Total votes 8 = included.
greenplastic: Total votes 2 = included.
suchmoon: Trusted by dooglus, Lauda, Blazed, owlcatz, The Pharmacist; distrusted by OgNasty. Total votes 5 = included.
achow101: Total votes 2 = included.
owlcatz: Trusted by TMAN, greenplastic, suchmoon, BitcoinPenny, krogothmanhattan. Total votes 5 = included.
JohnUser: No trusts/distrusts on DT1. Total votes 0 = included.
BitcoinPenny: Total votes 4 = included.
zazarb: Total votes 2 = included.
actmyname: Trusted by TMAN, Lauda, Blazed, suchmoon, The Pharmacist; distrusted by theymos. Total votes 5 = included.
The Pharmacist: Trusted by qwk, TMAN, Lauda, Blazed, suchmoon, owlcatz; distrusted by OgNasty, zazarb. Total votes 6 = included.
krogothmanhattan: Trusted by monkeynuts, TMAN, greenplastic, BitcoinPenny; distrusted by owlcatz. Total votes 4 = included.

So the final result is:
theymos
~~HostFat~~
dooglus
gmaxwell
~~OgNasty~~
SebastianJu
qwk
Cyrus
monkeynuts
TMAN
Lauda
Mitchell
Blazed
greenplastic
suchmoon
achow101
owlcatz
JohnUser
BitcoinPenny
zazarb
actmyname
The Pharmacist
krogothmanhattan

Special Thanks:
SFR10