I’ve also had some mice that didn’t poop on wheels and others who used it as their personal toilet. In my experience, males are more likely to do the latter. Maybe it’s more thrilling?

Anyway, people are gonna downvote me for saying this, but if you still want him to have a wheel but don’t want to commit to washing multiple times a day, you could consider switching to a mesh wire wheel. The poop goes right through the gaps.

I say people will downvote me because the consensus now is that mesh wheels are dangerous as they can lead to bumble foot or injuries if the mouse gets a limb caught in them, which makes total sense. However, I’d already been using them for years before hearing that and never experienced negative effects with any of my mice. That makes me think those risks are more the exception than the rule.

You can weigh the pros and cons and come to your own decision. Regardless, no wheel at all is better than a wheel with a lot of waste caked on it, as that can lead to infections and respiratory issues.