Yes, it's common. Yes, it's an issue when ordering wider tires. Yes, if you go REAL wide (i.e. 11" wide rims), you'll have to most likely order different backspacing on each side. And yes, it is the AXLE not being centered under the FRAME, not the body being crooked (although that can happen too....much LESS likely though).
(aka, the Search button works on this forum [img]smile.gif[/img] )
Go ahead and measure it. Chances are, in reality, it is only 1/4" to 3/8" shifted to one side and just looks worse than it is.