So, if you knew the guy had 88, you would be more willing to fold AA, more willing to play the KK?
Sorry, not sure what you are getting at here. You more worry about sets than 4 card st8's anyway, right? In which case, it does not matter if the guy has ANY pair less than your AA or KK, does it? And 4 card st8's are long shots, even when you make them.
That being said, If I have AA or KK, I would be more concerned by a guy holding 7-8 suited or 8-9 suited, as it is a far better hand against AA or KK; he could flop a st8, a flush (hope you got the 4 card flush draw with your aces or kings), two pair (nice full house draw), or one set (and another nice full house draw plus a long shot draw to quads!). Could flop an open ender (5-6/9-10/6-9 for 7-8) or (6-7/J-10/7-10 for 8-9). Suited, this could be a open ended st8 flush draw. Nope, if I see my AA or KK against 88, I am a happy camper. When I see that a small suited connector has called my AA or KK is when my you-know-what slams shut...
So on the flip side, if I am short stacked and have to shove into a possible AA or KK, I want it to be a small suited connector. Still, many will gladly take 88 and call an all in with it preflop. You can then lose to any higher pair or any two overcards that connect with the board. You can also get boned with 88 if the board double pairs higher (say 9-9-10-10-2, and the guy has J/Q/K/A-x), counterfeiting your 88 hand. Worse, with a 9 and a ten on a flop, lots of weak players will chase, you guessed it, the 4-card st8! Wish them luck with that, lol.