The only ticks I have had encounters with are ones on cattle and on dogs. In my experience, it isn't hair they go for... I have found them in short and long hair on animals, as well as relatively bald patches (like tummies.

The places the ticks I have found seem to have most success in are in places that it is difficult for the animals to reach... briskets, bellies, front and back leg "pits"...

I don't tend to get my armpits near ticks in this country... so no biggie for me. Move down under... no snakes, no scorpians, no stone fish, only three poisonous spiders..... and no armpit-lustful ticks!!!