A lot of people like tattoos for reasons related to taking a sense of ownership over their body (or subtler variations of that, like rejecting the sanctity of their body, or resisting external expectations applied to their body, within a specific social/cultural/religious paradigm).
Since many sex workers do a job that involves them granting access to their body, or using their body as a physical instrument, it's easy to see how such an act of claimancy might be appealing.
I'm sure many sex workers also have a complex relationship with aesthetics and presentation (ranging from their bodies to makeup to clothes to websites, etc.) and this could factor into tattoo appreciation for some individuals.
I think for others there might also be a healthy "fuck your rules!" aspect to enjoyment of body art/mods. Tattoos have a history of stigmatization in many cultures. Sex work is heavily stigmatized. If society is already telling you you're an outsider it can be fulfilling or liberating to lean into that and embrace a variety of non-traditional or taboo practices.