Wearing mohair next to the skin depends on the person -- and the softness of the mohair. Some of the first fiber I spun was some well-prepared mohair roving; it was plyed with wool, knit and felted into a hat. I can wear the hat about 15 minutes before I "feel" an itch from the mohair, but it doesn't bother me too much. Generally, I find mohair itchy next to my skin -- but that's just me, I know others do not.
Aside -- I've learned also that the "itch" can be useful -- it generates warmth! So a mohair scarf may be just the ticket to warm up a cold neck!
You could ask whoever you plan to spin the mohair for, to tuck some of the roving under a wristband or in a sock, and see if they find it itchy after a while. That's what my husband did with some of my wool when he said he'd like me to make him a scarf and I said I wasn't going to spin 100% angora for ANYONE once I finished the angora for his wrist warmers.
(mostly posted by me on spindlers, 12/3/2001)