When the board pairs on the river HU in Lo8,

[Murakawa]

I was just curious about what to do in a HU pot when you, let's say, flop the nut straight (and there is no low, or the low doesn't come in) or nut flush, and your opponent raises the flop and check calls the turn, and then the river pairs the board. I've been checking and calling (yes, he always has a full house) figuring that my read is good but with the pot odds he only has to be bluffing a failed low draw, idiot straight or flush or nothing about one in six times for my call to be +EV. (assuming preflop raise, flop raise, turn check/call).

Am I being stubborn or am I just questioning my play because I got rivered a lot yesterday?

Also, why are the .50/1 L08 games full of nits but the 15/30 games loose on full tilt?