Here is an example of an exchange that is NOT trustworthy, just for reference.
https://bitcointalksearch.org/topic/m.11515905Run by some guy called "Coldcoiner" from the Hastalk Paycoin forum, and has a couple of sock puppets here named TNTswap and Wunkbone. He constantly screws up and forgets which sock he is posting as.
Here are some red flags with TNTswap:
1. Located in India
2. Owner(s) refuse to identify themselves
3. Is aimed primarily at trading Paycoin and his new Paycoin clone "TNT", which he owns all of at this time.
4. The "exchange" consists of single wallet addresses that customers deposit coins into, and then send an Email explaining which deposits are theirs ( I am not making this up)
5. The address for depositing Paycoin is actually a Cryptsy address. He says this is because the Paycoin QT wallet does not function correctly. Again, I am not making this up.
6. The person running this is extremely mentally unstable and goes off on tyrades when people ask questions.
The list goes on, but I think you get the picture. There are about a dozen threads here filled with this guys lunatic ravings about TNT coin and TNTswap.