One witticism that I coined some years ago was to say to the customer "I could tile a basket ball if the tiles are small enough". They pause for a minute to think, but then they laugh and say "I see what you mean". That one comment has done more to break the logjam over the years when more intelligent and patient explanations of why what they want WON'T WORK in their house.
To them, it's charming, historic, authentic, and antique. For the tile setter, it's one big PITA in an old house.