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Villain had pocket 9's and flopped trips. Watched this villain later call HUGE pf raises with pp's. Once as much as $4.85 pf (about 1/3 of his stack) with 88, so rr pf wouldn't have folded him out or helped me "define" his hand.
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Generally you reraise with AK:
<ul type="square">[*]Because you want calls from AQ.[*] To give cover for your reraises with big pairs. Other times when you reraise with TT+, you want your observant opponents to hang onto underpairs in the mistaken belief that you must have AK.[/list]
You're not
unhappy to fold out small pairs, since they're technically ahead. But they're also kind of dumb to call without set odds, since they're going to have trouble calling your CB. And you're not exactly sorry they called, unless they're going to take their underpair too far (in which case you need to CB ace-high less and bet top pair/overpairs for value all day).
Someone who calls 1/3 of their stack with 88 is just playing bad poker unless they have reason to think 99+ is only a tiny part of the raiser's range.
Reraising to define your opponents' hand may not be wrong, but as you said if they'll call with 88+ then the information's not worth much. That doesn't mean not to reraise, though -- if they'll call with 88 they'll probably call with AQ or AJs, and when you both flop aces you'll be very happy.