In my years in the industry I've done my share of hiring and firing for both office and field people.
You want customers to be comfortable with the people they deal with from your company. Like it or not even though tattoos and piercings are more common place most people are not comfortable with a guy coming on their property or in their home who has sleeve tats, neck tats, face tats, gaged ears, nose, eyebrow, lip, or excessive ear piercings.
Same goes for office workers. Customers don't like dealing with a woman or man who has so much meat in their face and head they can't pass airport security.
My rule was generally not to hire people with face tattoos,or excessive tats or piercings that could not be covered or removed. If hired, sleeve and neck tats had to be covered while on the clock or on company property this included company vehicles. All piercings like eye studs, nose rings, gages, eyebrows removed. They don't fit into the business world yet. Personal I don't care what you do on your own time but when you come to work and I'm paying you you're on my time and my rules are the only ones that matter.