I'm with drug mentor and Pistachio on this one. I don't understand all the people saying how you have to 'play by the rules of the game'. This is an unregulated industry. There are no rules.
When someone starts dealing drugs, they must accept the possibility of them being 'dobbed in' by an unsatisfied customer. It is up to the dealer to maintain good customer relations so that this doesn't happen.
If I buy a load of pills from a dealer and they turn out to be crap, the dealer should give me a refund on any pills I have remaining. If they do give me a refund, I will probably keep using them in the future. If they refuse to give me a refund, I will not be a happy chappy, and they are obviously running the risk of me seeking retribution of some sort. That's their call, though.
As for the people saying you should beat up the dealer, why would I (or anyone) want to run the risk of getting arrested just to get back at some dipshit rip-off merchant? They're not worth it. Not only that, but if you do beat them up, you also run the risk of getting involved in an escalating feud, which could end up with you dead. Again, they're not worth it.
So.....from a moral perspective, I don't see anything wrong with dobbing in a dealer. In saying that, I have never done it.......yet.