Tattoos are an indication of someone with free will not tied down to some religious or moral dogma about not desecrating there body's.
A person with a tattoo tends to enjoy life more than a anal retentive individual who does what they are "supposed to do"
because a book or society tells them to. Tattooed people don't constantly worry and restrict themselves. People who get tattoos usually try to get tattoos that are unique to them and try to stand out from the norm. Perhaps it is not the women who are tattoo that are easy, but you.
I am a tattoo artists apprentice. I have met a lot of tattooed people, they are usually loyal to there partners if in a relationship, and don't act any different than anyone else except maybe a little more open minded. My guess is the tattooed women you say are easy were single bored and saw you as a mindless sheep they could kill some time with without becoming emotionally attached to you.