I don't think very many people care what other people do in their own homes. The problem arises when you are in someone else's home and you are served food on dishes that you - whether rightly or wrongly - don't think are properly cleaned.
If you were in a restaurant and you thought that a dish or a piece of cutlery wasn't cleaned properly, or your food wasn't properly cooked, you would send the item back.
When you're a guest in someone's home and you are trying to have a good relationship with that person, it becomes a problem. You have to choose between insulting your host and enduring what you consider to be unhealthy, or just unpleasant, conditions. (And if the host is an in-law, it can bring up a whole bunch of other issues.)
Personally, I have eaten food that I was mildly allergic to in order to avoid upsetting my hosts.