On this board you will find lots of opinions as to which places have better stuff than others, but I'm not sure I've ever heard of a coffeeshop that was a flat-out rip off, if by that you mean insanely overpriced pot, or pot that isn't pot, or hash that isn't really hash.
(Now the creepy street pushers...that's a whole other story...the short version is don't respond to them, in fact don't even look at them...just keep walking).
I think a lot of folks turn up their noses at the Bulldog places.
I've always had good luck at the Greenhouse (not to be confused with Greenhouse Effect...that might be good too...I don't know).
I hope it's OK for me to post this handy URL.
http://www.coffeeshop.freeuk.com/ACDfrmGu.html
have fun!
Neurosynth