Blocked sinks are caused by a variety of factors. Often, it's a simple matter of a buildup of food debris, grease, and soap scum. Over time, these substances can accumulate in the pipes and cause a blockage.

Other common causes of blocked sinks include foreign objects, such as toothbrushes or jewelry, that accidentally get pushed down the drain. In some cases, a blockage can be caused by a broken pipe or other underlying plumbing issues.

Regardless of the cause, a blocked sink can result in slow draining and unpleasant odors. It's important to address the problem as soon as possible to prevent further damage to your plumbing system.