I think the core issue in situations like these is that you are made to lack a baseline feeling of comfort in your home. Fear of germs can be a rationalization to justify the bad feelings, and it can also be used by others to dismiss your feelings. We each need to feel a baseline of control over our own bodies, and that can be disrupted by the persistent actions of others when those actions unavoidably affect us. I think that such living conditions can act as a sort of feedback loop, in which your need for a feeling of cleanliness becomes stronger in response to the grossness you perceive around you, while your attempts to get them to be more mindful of their actions might cause them to "double-down" on the very things causing your distress. You maybe only ever feel safe and comfortable in your room, or if it's shared with others then maybe not even there.
You are not unreasonable to have these feelings; your feelings are valid.
I hope your post at least grants you some assurance that you are not the problem.