How can you tell the good tattoo parlours from the crap ones?

look through the portfolios, you cant judge a book by its cover so just becuase the shop might not look appeazing on the outside, their might be some really really good talent in the inside, so go in there, see how their customer/client service is, look through portfolios, talk to them about their prices and such, watch for the tattoo artist just starting out lol they usually try and do work for cheaper then normal lol