If anyone insists on joining a P&D group they would have to be very disciplined and resolve to not wanting to make too much profit per each trade, and dont be greedy.
For example: Lets say you bought 0.01 btc worth of some shit coins that is about to be pumped, and now the price starts reaching and you discover that there is enough liquidity to market sell to earn 0.02 BTC or 0.015 BTC after paying Bittrex trading fees and you go ahead and perform that sell, now you have profited 0.005 BTC not bad for an initial investment of 0.01 BTC.
BUT... If you invest say 0.01 worth of BTC and you decide you want to be greedy as fuck and would like to sell when the price reaches the equivalent of 0.05 BTC or more because you see the purchases running up. Then all of the sudden the running up stops and is very quickly followed by rapidly "running down", the market is crashing because the "dump" phase has begun. At this point you are very late, you will HAVE to sell as a price much lower than your entry price, if you dont then you will have to resolve to holding the bag, your 0.01 BTC worth of bags is now worth 0.001 BTC
So, it IS possible to make money on one of these P&D groups provided that you get in VERY FAST AND QUICK, if the ticker had already sky rocketed too high and you aren't in yet, then forget it, skip this pump, it would be to the best of your interests to do so.
Okay, I have finished talking about Pump and Dumps. Now lets talk about another important RISK you will be getting yourself into if you decide to participate in any Bittrex P&D groups. Bittrex has been disabling accounts recently to thousands of users, as evidenced by many threads I have been reading here on Bitcointalk. This has been bought to my attention from reddit yesterday, I didn't knew about this until I came across a thread on reddit about international users getting their verified accounts frozen without any reasons and getting ignored by bittrex. I am a bittrex user and perform trades almost every day, and so far I have not been having any issues, but in the same hands I am in the USA and I am not read almost any complaints from USA customers getting the accounts blocked. Well anyways the point that I am trying to come across is that IF Bittrex comes to the attention that you are partaking in Pump and Dump groups they might freeze your account. Bittrex already sent a communication expressing their distaste about users taking part in Pump and Dumps groups in an email I received not to long ago (between November to early December). So participating in a P&D group is a great way to getting yourself into Bittrex' lottery where the prize is a chance of getting your account frozen. So THIS is probably the strongest reason to steer away from P&D groups.
Your possible question:
Q: How can Bittrex DETECT that I am taking part in a P&D group?
A: Someone from Bittrex might already be a member of the very same P&D group you are a member of, then can see what is the current coin being pushed for the day, they can analyze this data against the patterns they see on their exchange. For example:
"Bitcoin Diamonds" is being pumped, YOU go ahead and buy "Bitcoin Diamonds" from your Bittrex account and then sell them at a little bit profit, done.
Next day "Pink Coin" is being pumped, YOU go ahead and buy "Pink Coin" from your Bittrex account and then sell them at a little bit profit, done.
Next day ........... [you get the point]..
All this purchases of yours happens within 30 seconds to 2 minutes after that particular coin was published on the P&D group. It would be very easy for Bittrex admins to see, by analyzing your account's history that you must have been taking part in a P&D group and then can ban you accordingly. Also bittrex mentioned on the same communication I received over email that they can also give part to the authorities, so taking part in a Bittrex P&D group can not only risk getting your account suspended, but also can risk you getting into legal trouble.
So, to do or not to do? Dont do it.