Underexposed?

In reading other people's critiques I quite often see a comment that a photo is slightly underexposed, and I think it looks great. Or, they talk about how they feel the photog 'nailed' the exposure, and I think it's just a tad overexposed? Seems to be pretty consistent, though.

My monitor and/or calibration, maybe? My eyes and how I see things?

My monitor is not calibrated at the moment.

personal preferance?

Go to dpreview.com and look up a camera test, like a Canon dSLR. On the first page of each test, at the bottom of the page, is a 26 step grayscale. Adjust the brightness and contrast of your monitor so that you can see the 26 steps and (ideally) differentiate each of the steps from the adjacent one. That is a very good starting point, and will go a long ways also to getting commerical prints that look like your monitor

Most people over brighten the monitors. It is easier tosee it that way. but the colors are not right. I know I had mine to bright. Big difference when I started calibrating it. Start with what Wilt suggested.That will get you a lot closer, not exact, but in the ballpark.

I'll check out that thing Wilt suggested. I do know that when some photogs put the test scale on their websites I think they always look just fine and I can tell a disinct difference in each color from black to white.