In this month's home inspection picture we see two issues. First, the sink basin has an "alligatoring" effect in the sink and is very worn. The second issue is a slow drain. A slow drain is usually easily remedied by drain cleaner. But if the problem persists, is in more than one or two sinks, or lasts for a long period of time, you could have a main line clog and you should immediately contact a qualified plumber.
Devereaux Van Dyne, Certified Professional Home Inspector