Other celebs who used to ski at my place (any place where I've been more than once is "mine", but in this particular case I'm talking about the Dolomites, where I've spent at least a week per winter since I was a kid) :
-David Copperfield and his then girfriend Claudia Schiffer
Never, ever saw them, or better, like Donadonis' case, never took notice of them
-Massimo Lopez. He's an Italian comedian/impersonator. My ski buddies and me used to while away, in the late afternoon, till the lift close time in a mountain bar.
One day this guy shows up, and start to chat with us. He's fun and a kind person. Obviously he was recognized and asked to do all sort classic impersonation. I hear he still spends his week ski trip there, but never saw him again.
Probably I never recognize celebrities, even if I deem myself a sharp observer, because:
1) I don't care
2) In the rare case I notice, then I try to treat them as normal people.
I think they too are entitled to their own privacy and a bout of anonymity, sometimes.
Of course there are those who feed their ego mixing with people, revelling in the attention that they attract, and in such cases, I make extra efforts not to take any notice of them.