[Crazy Jetty]

Packaging errors (unless they're silly, like the figure is packaged upside down or backwards), or minor color variations, such as someone's belt being a slightly different shade, do not interest me.
Production errors only interest me if it's something unique, sunch as the recent DS Enterprise-B being labeled as the Excelsior.

When the "varient" is a chase figure, then I only care about it if it's something I care about.
I'm of the mind that those kinds of chase figures should then be something that only hardcore collectors would care about. The Amazing Bagman as mentioned above is a great example. Can't imagine that being anything more than a shelfwarmer if it were the main figure, but has huge appeal to the hardcore fans out there. It's something that doesn't appeal to everyone.
I also like varients when they get multiple costumes out (but usually in 50/50 ratios), since as Marvel Legends Angel coming in both blue and red costumes.
But in such cases, I usually pick up what I can find.

What I don't like are when the version that should be common is made rare. Such as DCUC Sinestro. His iconic Sinestro Corps version was impossible to find, while his classic costume just rotted on pegs. It should have been the other way around. (And I don't just say that as sour grapes because I never found it. It really made no sense, now or then)