Why Does My Cat Lick My Hair At The Slightest Opportunity?

Its a sign of affection. Befor a cat an see all it knows is its mother grooming the, so he might do it to comfot you or tell you that he thinks your part of her family. If they get a bit obsesive then it might be something else or she just really loves you, try taling to your vet
rose

Both of my cats chewed on my hair, the female more than the male.  It usually happened more if I had gotten my hair colored, or some other treatment.  I tried switching brands of shampoo and conditioner, but it wasn't the brand, it was just the fact that they liked chewing on my hair.  Even at 17 years old, my female will still do it occasionally.   

Cats are very clean in nature, and they are always cleaning themselves, mine clean me too. Though it isn't my head, they sometimes go for the nose or the chin and always around my watch.
It is just that you are part of the family to the cat, and with that said, you are getting bathed, just like another part of the family might get it too. Sometimes they do like the smell of something, but I would just set the shampoo and the conditioner on the floor and see if the cat goes to one of them or both of them. If it appears to be that, then change brands. Hope this helps, good luck.

This does not sound like a fun issue.  Try switching the type of shampoo and conditioner that you are using.  She might just be attracted to its scent.  Generally this type of behavior is just your cat's way of showing affection!