While this really should be #1 if we’re being perfectly honest, until you’ve actually gone through the search to find a makeup artist and sat down with one, you couldn’t possibly assess their level of cleanliness. Here are some things to look out for when assessing the condition of their kit and practices:
Are their products tidy and not covered in makeup dust and goo?
Are their brushes clean? A minimal amount of staining is normal on brushes that have white fibers, but if the brush LOOKS dirty, it’s probably dirty, and a great vehicle for spreading bacteria. (gross)
Also make sure that your artist is sanitizing brushes between services (yes, that means before every one of your bridesmaids).
This goes for beauty sponges as well.
Your artist should never be working directly from the wand that comes on the mascara they are using unless it is your personal one you are keeping. Disposable wands and mascara brushes (that are cleaned between each client) are a MUST.
The same thing goes for eyeliner, lipliner, and lipstick. Each item should be sprayed with isopropyl alcohol and wiped clean before use on a new client.