When I read your descriptions I thought the same; there might have been a dissolute sort pleasure for the owner in looking at these. But after seeing them, it strikes me that there may be a puritanical streak to these after all… each tile could be interpreted as illustrating a sin to be avoided (except possibly for St Jerome, whose story I’m not familiar with–maybe the nobility of faithful suffering?). The fact that they’re in the firebox itself is what led me to this interpretation… with the flames flickering in the midst of all these temptations it could be a reminder to the unwary of what may lie in his future!