Sunless tanning products will not normally discolor hair.  But if hair is very porous, and/or white, blond or grey, then it can absorb the solution and become tinted.

The prevent this, light or porous hair should be covered with hair cover.  One can also apply a cream hair conditioner to hair roots to help protect them, as needed.

Bald heads can be “tanned” but the client needs to exfoliate them well first.  A baking soda scrub with a washcloth will generally work well.

If the client has thinning hair, that is light colored or grey, advise them to coat hair with a thicker cream conditioner.  Don’t rinse conditioner out of hair.  You can also use a barrier cream or some mild liquid hand soap if they forget to coat hair.

When showering, rinse conditioner from hair.

DHA has a distinctive “yeasty” smell while developing.  Some people never smell it; with others it can be quite strong and unpleasant.  It is not just the product, but is also related to each persons individual body chemistry.

Most people don’t notice odor after showing, but some may smell it lingering for days.

Probably because you don’t have twelve makeup artists and four hours to get your “look” perfected.

That is what is needed by the average model or celebrity before any photo shoot, or major public event.

Many anti-aging products for facial skincare also contain skin exfoliates.  This means that they will cause your tan to fade faster and more unevenly, in the areas of use.

With a spray on booth tan, the client needs to position themselves properly and turn as needed to be evenly colored.

This can be tricky for the beginner, and the staff may not be properly trained to give them accurate advice.

Fortunately with any spray on tan, the skill of the technician will dictate the outcome.  With the booths, you will usually always be sprayed the same, even when you go to another facility with the same equipment.

With hand spray, you go to a good technician and come out looking great!

I personally don’t advise UV tanning in any circumstances, for anyone, regardless of the skin type.  The very real health risks make this an unsafe alternative for everyone.

These are all situation that alter the way the eye “perceives” color tones, and the way light reflects from the skin surface.  If your tan looks fine in other situations, know it is related to the unique lighting situations that dampen some of the color spectrum, and image flattening 2D related to photos.