His breath has no smell, presumably the rest of him is much the same.
TALUR: Hmmmm. Remarkable set of teeth. no sign of decay. (sniffs) Breath smells like. (puzzled) Well, it doesn't have any
TNG: Thine own Self
Data has a scent, but it's not one that's especially noticeable.
He bore no scent save that of a freshly laundered garment and a hint
of bioplast sheeting. Nonetheless, he looked uncannily human, down to
the pores of his skin.
Star Trek TNG: The Buried Age
All of the Enterprise crew (including Brent Spiner) absolutely reeked of body odour and cleaning fluid, at least for the first couple of seasons. The spandex fabric they used for the uniforms resisted cleaning except with harsh chemicals that could only be used once or twice a month. For the rest of the time, the cast were expected to sweat into their suits which would be spot-cleaned.
"Spandex retains odor, so there is a certain part where if you’re
wearing them for a long period of time, you can’t really clean all the
smell out, and it becomes a little bit annoying. And it also retains
the odor of the dry cleaning fluid. It is, on a day-to-day basis,
Bob Blackman, the costume designer behind the show’s iconic uniforms