I have no where left to turn. What the hell is offsides in soccer? I've watched and watched and watched, and I just can't figure out what all the offsides calls have in common. Each time I watch either someone does something that I think is blatantly offsides and no one blows a whistle, or a whistle sounds in the middle of what looks like an entirely legit play. I just can't figure it out.

Simply put, whenever a pass is made (at the moment the ball is kicked), if you are an offense player (member of the team with the ball) then u need to have a defender between you and the goal.
It is the linesmans job on the side of the field to make these rulings. He should be even with the last defender at all times.
The tough part of this call is that in essence you need to look at the last defender, the offensive player and the player kicking the ball to catch the exact moment.
If you have a chance to catch English Premier League soccer coverage or ESPN's champions league coverage, they have been extremely good at showing replays of offsides calls.
Hope this helps.

OK, that would mean that if there isn't an offensive player between you and the goal it doesn't matter where the defensive players are, correct? i.e. a break away offensive player can't be called for offsides.

If you mean, player with ball goes past defensive player or players by himself, you are correct.
Another visual tip that might help---
take the last defense player and draw a line
across the width of the field. If your team has possession of the ball, you cannot go across that line until the moment a teammate kicks the ball forward.