If you shower in the evening before bed, how dirty do you get while sleeping? The alternative is rolling around in your bed all night with all the grime of the day.
My hair doesn’t look presentable at all if I don’t clean it in morning. It gets all greasy and dark (I have blond thin hair). I never saw an Asian with that problem before, they can just wake up, wash their face, and walk out.
On the other hand, before I visited China, I never imagined getting so dirty that I needed to shower before bed, or I would be rolling in dirt. The dirt really gets on you in dusty Beijing. It wasn’t what I was used to from the states at all.
Full shower in the evening. I stick my head in the shower in the morning to get my hair wet and wash my face. Otherwise my hair looks like an anime character.
I guess it depends on whether the primary contaminant you're worried about is dirt from outside (in which case you want to wash in the evening to keep your bed clean as you describe) or sweat (in which case you want to wash in the morning to avoid smelling sweaty while interacting with people).
For me, the latter is much more a concern - I sweat overnight and so want to be clean in time to start interacting with people. If I do physical activity, or it's a hot summer day, I might even shower in the morning and evening.
On the other hand, before I visited China, I never imagined getting so dirty that I needed to shower before bed, or I would be rolling in dirt. The dirt really gets on you in dusty Beijing. It wasn’t what I was used to from the states at all.