Another Approach
Nat,
In general, the advice given above by Bootlegger is solid, and is in fact what the vast majority of advantage players do in the situations you describe. I regularly find myself ignoring the pleas and curses of the other players... this is yet another good reason to play heads up!
However, you might wish to try the following approach, which I in fact used on occasion back in my early days...
Say you have 16 vs. X, you have $25 in the betting circle, and the OKIA (that's "obnoxious know-it-all") has a much larger bet, say $500. Hestitate before you make your play, as if you're having trouble deciding what to do. When OKIA finally tells you to hit, tell him, "I was planning to stand, but if you give me $25, I'll take a hit." Of course, if his advice is to stand, tell him just the opposite. Make clear, though, that the $25 is simply your fee for following his counsel... you still get to keep any money you happen to win on the hand, too.
If OKIA falls for it, by all means follow his words of wisdom. If you win the hand anyway, you've just made an extra $25 on a truly crappy hand; if you lose, you at least broke even, which is twice as good as surrendering. As long as OKIA is willing to "finance" your "education", you're living on Easy Street. Develop a sudden case of amnesia concerning the B.S. tables, so you have to "think" about every hit/stand decision, and you'll rake in an extra fortune at his table. Follow his advice for even really bad plays, like standing on 13 vs. 7, since you know you'll at least get your money back. Don't even worry about counting the cards or making index plays... you'll do much better getting OKIA to pay for your "lessons".
If OKIA spurns your offer, perhaps he'll finally come to realize that you don't appreciate his advice... probably not, though! This is why all AP's eventually develop a thick skin.
Hope this helps... that'll be $25, please ;-)
Dog Hand