What if they raise when they are first to act. It could mean they are betting overcards to protect them from a draw or a semi bluff of sorts in which case you are well ahead in the hand.

I was involved in 2 big pots with JJ. Both were all undercards, but when i got reraised on the flop from my utg bet, i became suspicious. I folded after the flop after i made a raise, and he reraised. He showed KK.

ANother time however, soemone played it the same way after the flop except, he didnt reraise before the flop. I still opted to lay it down to be safe...He showed TT.