You people are missing the point of my original question/statement.
I am sending lenses to CPS repair after purchase and just asking them to "check autofocus". I am not telling them that their IS a problem. However, Canon almost always identifies a problem on their own and fixes it.
Several years ago I was told to do this by a CPS rep at a trade show. Since then, I have done it soon after purchasing a new lens and the majority of times Canon has found something that was not up to spec.
It wouldn't surprise me at all if they're trained to say they did something (of significance) even if they didn't. It's customer care -- you want to make buyers of expensive components feel cared-for.
Your assertion would have some meaning if you had tested it thoroughly before and after, and had found significantly different performance.
Exactly. The poor guy has something wrong with every single lens... while most everyone else on the thread has had zero issues. 1. Buy a brand new lenses (How many is anybody's guess). 2. Send it (them?) straight in for service. 3. Canon finds something wrong with it (All of them? How many?). That really sucks. Glad he ran into a trade show rep who is there to promote the product that pulled him aside to say, "You know, our lens QC really sucks. You should send every lens in and have the service center check AF. Our product is so bad, trust me, they'll find something wrong. Keep buying Canon though!"
Interesting, CPS finds a problem every single time... but the CPS member hasn't stated there was anything wrong to begin with.