Like always, it depends. In a raised pot against tight players, I would be confident the flop missed them and they have overcards, but against an aggressive player in late position who raised preflop and was first in, he could have anything, so I would play it cautiously. Of course there's a big difference having the ignorant end of a low straight and having the ignorant end of a high straight. I would be much more aggressive, in general, holding 23 and floping a 6 high straight, than holding 89, and floping a Q high straight, as players are more likely to be playing high cards than low cards.