Well, maybe not completely unbiased, but factual and reasonably balanced. The moment a salesperson spouts an obvious lie, his (or her) credibility is ruined and that causes me to question every other statement they've made.
"Nobody else has this feature" is one such lie (or simply a mistake, easy to do if you don't keep yourself up to date on what the competition is doing). I'd be much more inclined to trust someone who can say "Well, <competition> has a feature similar to this, called <X>, but I've used it and I personally find that Apple has done it better because ____".
I also respect a salesperson who is able to say, after assessing my needs, that maybe their product isn't right for me (without it being an insult).
Generally, people who listen to what a sales person says, are naive. Nothing wrong with asking simple questions (e.g. what cable do I need), but if you trust everything any salesman says on a major purchase, then that's your own stupidity. If I were to buy a new oven, I'd do my own research on the best brands and find as many reviews as possible. I wouldn't just waltz in to a store without a clue and go with whatever the salesman suggests. Because if I had had a different salesman, I'd probably end up with a different oven. There's no such thing as an unbiased neutral salesman, commission based or not.
Factual is another thing. I agree that those who work at the Apple Store tend to be not the most technologically bright people. But then, I've been to a hard floor store, and had a salesman who couldn't tell me if that flooring could be screwed down onto a joist at the teeth (which most do, only some that don't).