Playing long enough to know a couple of things. The over bet flop is usually not a
bluff, the over bet river, depending on the card that just flipped usually is. Especially true in cash tables where they have committed to much cash on their missed draw and are trying to get them back.
I do not agree with previous replies.
The over pair would not be over bet in response to your bet on the flop. The over bet would not be made in response to your bet on the flop on a draw. The over bet is for value on a made hand blocking draws against players they figure as fish and will call. Your PF and pot sized c-bet was a good indication of a big pair and a message to the other player he can get and will get a call. The net was out in the water.
Lot of money to made with the right response to the over bet, people screw that up all the time.
You need to think are they over betting for value or as a pure bluff.
You will never see the over bet on the flop as a bluff by anyone other than a total retard. I would only call that over bet with a top set myself, but depending on my mood I will call with a strong draw to the nuts.
The river on the other hand.
What story have they told you thus far. If it's a changing story on the river, they missed.
If you have extra dough, the story has changed with what they have represented earlier streets, you can call the over bet, its a complete bluff with air, but does the board also represent the complete nuts?. Its a tough call, but it is profitable, lots of players do this far to much. Think of it this way, the over bet is only done for 2 reasons, nuts or pure air bluff on the river. Go with your gut.
But I don't blame you here, it sucks to run into someone who has made their set, but you have to consider it always.