Can split testing be trusted? No, not if you misunderstand the most basic concepts. Non-statically significant results are, surprise surprise, not statically significant.
They hear about it, run off and implement the a/b versions of their pages and add some tracking. Proceeding then to draw incorrect conclusions and make bad decisions based on them. They don't go read up on it enough to understand the statistics behind it. I used my stats book from Uni (I knew it had a better use than a laptop stand, a java book now has that honour) but there are plenty of tutorials out there. For example: http://visualwebsiteoptimizer.com/split-testing-blog/what-yo...
It really is a toss up between statistics and medicine for which is the most misunderstood of the sciences.
That's why sites like Visual Website Optimizer are getting increasingly good. They use plain language to explain when to keep running the tests.
Again: It's unrealistic to expect lay users to learn statistics. They don't want to become statistical experts, they usually just want to increase sales. This is where software can help.
As an aside, wow another one of my favourite bloggers responding to a comment of mine on HN this week!
EDIT: I just noticed your username and I realise that you probably already understand this :p I still think it's a bit of an odd way of putting it though.