Hi violetbat
Yes just as you said - I was advised ( in 2015 when I first started using it) to apply T gel to my upper inner thigh, but was warned I might get dark hairs there.
Not only did they grow there, but all over my thigh ( T is transported through the skin as well as being absorbed into the bloodstream through the skin) - which was a right pain. So I changed to the inside of my knee but continued to be quite hairy. Since I've never had much of a problem with excess body hair in the wrong places, I changed again.
Now - thanks to sheila99 on here who started this off - I apply to the soft part of the inner sole of my foot and I have not developed hairy feet!
Personally I wouldn't apply anywhere near any sex organs or anything like that as I wouldn't want any localised side effects and in fact actually developed interested sensations in the nether regions when I applied to upper inner thigh

Hurdity x