There are some great homebrew stores out there, but in my experience (not to mention the stories I've heard) the amount of bad information some store owners and employees give out is staggering. Especially when the most common argument for shopping locally rather than online is the advice you get.
A few gems:
Liquid yeast doesn't need a stater unless you are brewing a barleywine.
"You should bottle straight out of the carboy. Bottling buckets are known for contamination and there's no way to truly sanitize them. If you use a bottling bucket, you WILL get an infection."
Three piece airlocks are obsolete!
"They tell me I’m going to infect my entire house and unless I want to only brew Lambic styles, I should stay away."
I don't know if these guys stopped reading brewing books in 1987, or if they've just drank a few too many homebrews over the last few decades. It seems like if this was your job and your passion you should put a bit more effort into staying on top of the latest trends, techniques, and ingredients. The better the advice is you give, the more brewing success people will have, and the more repeat brewers/business you will create.
Luckily these days I'm happy to talk to Derek the owner of My LHBS in Falls Church VA, and the whole gang at Maryland Homebrew in Columbia MD. I won't say I always agree with the advice they give, but most of the people I've talked to at these two shops really seem to know what they are doing (although it is pretty rare I go in looking for advice these days).
If you've got a good homebrew store horror story post a comment and let the rest of us hear it.