Radio Free Albemuth. Not exactly his best novel. Yes, if someone picks some random Dick novel, he's likely to be disappointed and your criticism of such a random Dick novel stands a good chance of being correct. I think the same could be said of random Dick short stories as well.

Setting those aside, I think your argument is harder to make where his best novels are concerned.

That said, I'd be interested to hear what you consider Dick's best short stories. Most of the ones I've read have been pretty disappointing (with the exception of a couple I cited elsewhere in this thread).