I've done some CTA wording tests for a client selling event tickets. We tried "Buy Now" vs "Find Tickets" - "Find Tickets" gave us a huge lift in revenue (not just clickthroughs), probably because the language was less committal and was more successful in driving traffic down the funnel. /anecdote

This. I haven't seen meaningful lifts from changing button colors, wording or all these things I read on guru blogs. Most (all) of the tests I've seen reported on blogs fail miserably at the statistical test, not to mention no DoE, no blocking, no theory and a thousands other things that made the test invalid.

The only way I can see that a change in colors or wording would provide a lift is if the original was confusing, which shouldn't be the case.

While I generally agree with you. I have seen adwords tests where extremely minute changes in wording caused statistically significant increases in conversion. The biggest had to do with a campaign with the word "seeds". For whatever reason, changing the plural seeds to a singular seed doubled conversion.