Affiliate Marketing Secrets

No and yes no and no.
No it is not a niche business. Very few people cut their own hair…so the hair business is a universal business, not a niche. THough certain hairdressing styles can be a niche (African hairdressing in a mainly white city, English speaking hairdresser in China…that sort of thing).
Yes it is niche because most of your customer base is in the local area (people go to their local hairdresser)
and finally no, because the best way to promote a hairdressing business is to give people a good haircut, their friends say “I like your hair cut, tell me where you went” and may cross town to go to a good hairdresser.