@BettyBardMacDonald
I don't care if the world has the same standards, but the people here scoffing and sneering at the OP, and doing their competitive mingingness to prove they aren't "snobby," is pathetic.
It's the dismissing of the OP's concern that is annoying. I don't care if the rest of you wipe down with the same old T-shirt you use to line the cat's bed. But her concern is valid, and she did say that her husband outright laughed at her instead of supporting her. And the boy is quite old enough to be considerate of others, especially in a shared bathroom.
It's not dismissing the OP's concern to point out that the reaction was grossly disproportionate and self-defeating.
Regardless of how important towel hygiene is in the hierarchy of needs in a family (you think its very important, I think its less), surely you can accept that it takes a back seat to good relations and harmony in a family. Anyone with an ounce of self-awareness will understand the pitfalls of step-parenting and the need to tread with a degree of caution and sensitivity.
I don't think anyone is saying the OP shouldn't have challenged this boy on it. We're saying she shouldn't have torn him a new one over it. It really isn't, in the scheme of things, worth poisoning her relationship with him. He will for years remember than she chose to fly off the handle about this towel thing, which is pretty petty, she probably won't. She's diminishing her own emotional and moral capital with this kid by making a mountain out of a molehill.
And if, God forbid, this kid gets into much more serious trouble down the line, she will have lost his goodwill and the right to be taken seriously by him.