I had to clean out the drains to my master bedroom dual sink vanity over the weekend. My wife's side was slow. Mine was OK. As per typical, it was sludge build up on the tailpipe and after the trap. The trap itself was clean. I started with baking soda and vinegar followed with boiling water. Which actually made it worse as I think it did a good job of cleaning the tailpipe and sent more crud further downstream. I had to break out the big gun at that point and go chemical. After a jolly good dose of ZEP drain cleaner followed with boiling water it is flowing free and clear now. Does anyone have a regular maintenance program they do on bathroom sinks to keep them running clear? I shave in the shower so the main thing going down the drain is water and the by-product of brushing one's teeth. I pulled the trap out and it was clean even before I went chemical. There wasn't any hair build-up. That has been a problem in the kid's bathroom due to my daughter's longer hair. My wife and I keep ours pretty short.