How does escrow protect against the kind of scams that craigslist allows for. Also, how am I supposed to know if something is a scam on craigslist??

I got another email today about my rig.

"Hello,
Thanks you for the response, I'm  okay with condition  on the
Craigslist...I am ready to make instant purchase. My mode of payment
would be in Certified Check  and i will arrange for a local pick up as
soon as you get the payment, . I really wish to be there to check out
the item but due to my work frame i can not be able to get there , am
very busy woman (Nurse) and i don't mind adding an extra $50 dollars
for you to take the advert down from Craigslist, so that i can be rest
assured that am in hand of  it. More so  my husband  will process your
 payment    as soon as you provide your information ,and i promise
everything  will go smoothly,  Concerning the pick up, i will arrange
for it after you  receive the payment  and it clears... Please get
back to me with below info  so that i can proceed with the payment
immediately if you are selling to me.

 Name: Name to be written on check
 Physical Address: Not P.O.BOX...
 City: State:
 Postal Code:
Phone Number that i can send text
How much is the amount of the item:

And as soon as this is provided, the payment will be process  tomorrow
 and i will let you know when its mailed out. Thanks and i hope we
handle this in good faith.Additional $50 will be added for  remove the
item from the list.I will happy if you can sell the item for me.
although this is first time in Craigslist, So please be honest with
me, thanks for understanding, looking forward to hear back from you
..God Bless you

Regards.."

How should I know if this is a scam or not??