Using Sinks Question. ???

I think its because every room gets automatically classified as a kitchen. I think this cuz whenever I go to save a room, kitchen is the default option they save as and I'm not 100% sure but i think if you save the rooms near the kitchen (or bathroom) as something else, your sim will be more likely not to wander to a different sink. Sometimes it works sometimes it doesnt so I'm not sure if its just chance but its worth a try.

I think quality of the sink matters too. If a sim has a bad bathroom sink and a nice kitchen one just a room ocer they may be more inclined to use the better one.