"Scruples" doesn't really apply to a neutral medium, just content. And it applies more to the artist than the client.
Suppose Kelly Christian opens a tattoo parlor, Living Epistles. S/he does a few tats for church friends right away. Once or twice a month, s/he gets another Christian or benign commission. Somebody comes in.
- "I want a flaming demon head across my chest..." "I don't do demons."
- Another, "I want '666' tattoo'ed on the back of my hand..." "Not here."
- "I want a stripper on my bicep, so she will dance when I flex..." "We don't do porn."
- "I'm a Capricorn. Can you put that on the top of my breast...?" "No astrology here."
Soon Kelly notices that s/he's turning away more clients than s/he's accepting. His/her business is losing money and overhead costs are looming.
His/her choices are either
- Diversify services in order to stay busy when there is no acceptable tat commissions available,
- Expand services to include darker-themed commissions, or
- close his/her business.
If #1 doesn't take off, #2 becomes a real, recurring temptation. That is where his/her scruples might be abandoned.