Bathing/Grooming in the TOS-era

[Mytran]

In terms of grooming, we do see some kind of built in vanity unit in Uhura's quarters, in I think "The Tholian Web"?

That same rotating unit was in every cabin on screen, since it was part of the standard "captain's quarters" set.
We do get a good look at it in TTW though

 

[scotpens]

. . . Given how often Kirk got banged up, I think the substance was probably more a medical cream he kept available on his dresser, than a cosmetic.

Yes. According to the script, the double finds medicated skin cream in Kirk's quarters.

Maybe it's Clearasil and Kirk secretly suffers from adult acne.

 

[Ceridwen]

I have trouble seeing Kirk as a "metrosexual."

1999 called, they want their weird kinda homophobic slang back. It's the 23rd century! There's no reason to project those kinds of hangups on him, especially since you have to reject something seen on screen (his makeup kit) in order to do so.

 

[JonnyQuest037]

Yes. One was a horrible creature that caused Kirk to scream in intense pain, and the other one was Nancy.