its a tough call. there is a market for every product. my good friend owns
http://materialbitch.com
its a niche market. and he makes a KILLER living off it. granted its not on a vehicle in traffic.
this may tell you something as i have offered him to wrap his car for free as we go back years. his response was that he wants NOTHING on his vehicle to do with his site. EVER.
the medium is everything. a website offers anonimity. a car doesnt. ethics aside, do what you have to do to make money. your clients efforts do not reflect your own. you are there to provide a service.
if you didnt believe in god, but a client asked you to wrap their car in a jesus theme, would you object? or are you there to provide a service?
we are all adults. our methods are our own. i dont care what you bring me. its ink and media. if you are a paying customer, ill do what you write a check for me to do. whether or not i will bring it into my life and put it in my portfolio is a different question.
but at the end of the day, im here to provide a service. and im not here to judge or project my ethics or feelings on to you. friend, foe, or customer.