[AdamK]

I think Dimitri is correct in saying that you cant be wrong in either calling or folding.
ie.it’s close; if you’re 90% sure you’re beat then pot odds justify a call, and folding won’t cost you
much either.
However, I play a lot of heads-up stud and used to have a policy of always paying off on the
river in this situation.
A couple of days ago I played a regular customer which I had mental notes on saying “never bluffs on the river.”
I bet Aces all the way til check-folding on 7th ( and was quite happy in doing so).
Did the same thing a few hands later...
About 2 hours later I’d gone from being $600 up to about level.
It was the next day before I realised this guy had turned from being someone who never bluffed on 7th,
to someone who was probably robbing me at any opportunity.

It was a bad day, I played like a wuss and am reverting back to my old policy of always paying off.
I know playing in ring games is much different - just something to think about.

In a ring game, if he makes it 3 bets on 6th you call and can happily fold unimproved on the river.

To summarise, if you keep folding unimproved big pairs on the river, it may become a mathematical disaster.
Do it once, but be careful in folding more times than pot odds justify.