Is there a website I can visit that will describe where different off-flavors come from? For instance, if the beer tastes malty, fruity, or bitter, where can I go to determine why?
How To Brew by John Palmer contains a good summary of common off flavours:
I'm writing various articles about this on my blog. Not as many posted yet as I'd like, but I also have a life and a job to attend to. Look up the "Fishbone" diagram on my site for lots of good information about sources of quality issues in beer.