Or to quip: could slaves be patrons of baths?
There are a number of sources which state quite clearly that slaves could use the public baths. First, this from a blog from the University of Kent:
The rich, who had no time constraints, could choose to bathe at the optimum time and therefore temperature, but labourers or slaves — who were not in control of their time — had to settle for a tepid bathing experience once their work was done.
And this from Sandra R. Joshel, Slavery in the Roman World
We know that slaves could visit the baths, if they had the fee...
And this from the a French regional (Limoges)school authority blog:
Everyone was allowed to use the Roman baths – even slaves.
Granted, this last might not be the most authoritative of sources, but I was unable to find any sources that say slaves could not use the public baths.
Here's another source, this one in French:
Ce qui est sûr, c'est que, malgré la rigueur de sa condition, l'esclave prenait gaiment la vie. Celui qui habitait la ville n'était pas conflué dans la maison et rigoureusement enfermé dans les travaux domestiques. Il participait à l'existence joyeuse de son maître, il fréquentait comme lui les bains publics, il assistait aux jeux du cirque ou de l'arène.
Translation What is certain is that, in spite of the severity of his condition, the slave could have a happy life. He who lived in the city was not confined to the house, nor was he strictly confined to housework. He participated in the joyful existence of his master, he frequented the public baths as his master did and he attended circus or arena games.
We know slaves were allowed within the baths, but the question is could they use the baths as customers. First of all, there doesn't seem to be any writings concerning regulations forbidding the use of the baths by slaves. We do know however that, even among Roman Citizens, access to the baths was regulated. The baths charged an entry fee.
They were public only in the sense of being open to all citizens who could pay the modest fee demanded for their use. Free baths there were none, except when some magistrate or public-spirited citizen or candidate for office arranged to relieve the people of the fees for a definite time by meeting the charges himself.
The Private Life of Romans, By Harold Whetstone Johnston
This would indicate that a slave would have to be of such a status that they may have had (or been given) the required fee to make use of the 'public' baths.
A good source which looks at the possibility of slaves as bath customers is the book
- Bathing in Public in the Roman World By Garrett G. Fagan, pgs 199-206.
Evidence presented seems scant, but does list a few occurrences of slaves using the baths. Again these instances that we have record of, were slaves of 'higher status'. There are also some good notations concerning special circumstances such as slaves in a mining region having certain hours set for their use of the local baths, indicating this use was allowed. From pg 204:
It is noteworthy that in all of these instances, the slaves in question either stand high in the slave hierarchy or enjoy close proximity to their owners; there is no evidence that menials would have had the same opportunities as these fortunates.
So it seems that if a slave had the status to have the entry fee, there was nothing forbidding his use of the baths on a customer level. But the scarcity of records supporting this would seem to indicated that it was not 'the norm'.