Tonight, after Trials of the Grand Crusader (four down, bug to go) we decided to hop onto some alts, which led to back to back TotC 10 on my DK and Shaman. Then back to back Ony 10, also on the DK and Shaman. And because I'd spent hours in TotGC 25 on my warrior before that, by the end of the night, I had no idea what class abilities I had anymore. Between popping Army of the Dead when they called for Heroism (it's bound to the same key) to trying desperately to use Chains of Ice when asked to Frost Shock the Ret Pally, I was in rare form. And it wasn't just me, either: the druid healer is usually a mage, the warlock raids as a priest, and the holy paladin healing the second Ony attempt has something like 10 alts at 80. I'm surprised he even knows where he is. We got it all done, mind you, but you can really tell the difference in smoothness between our mains and our alts, even as well geared as the alts often are.
So now I put it to you, gentle readers. Do you ever suffer from class bleedover? Are you ever on your druid finding yourself mashing the Consecration button, or on your Mage trying to use Hymn of Hope? Or do you find it easy to keep it all straight?