I cannot say if buddhist tattoo is acceptable or not, but its still up to individual as it is very personal. If we think the skin as just a piece of white paper to write anything we wish onto it then in my view is accceptable. But the only thing is how do we treat the tattoos such as holy images of buddha and mantras. Do we use them as a reminder to our practice, which is important....and very fundamental. Holy images manifested out of compassion as a reminder to attain the qualities of the Buddha, Dharma and Sangha.