Adding insult to injury, you don’t know this is happening because, usually, it’s all out of sight.
The worse part of looking for leaks under sinks is there is usually a bunch of stuff down there, and you will have to move it around or — better yet — remove it all completely so you can do a thorough inspection.
Here’s what to look for. Look for warped wood, boards, water rings, or other signs of water damage. Use a tissue paper to wipe each pipe connection, both supply and drain. Any type of moisture will be detectable using tissue paper. If a supply pipe is leaking, that’s dangerous because there is pressure that can cause it to steadily increase the rate of the leak. For the drainpipe, gently shake it to see if it is loose. Drainpipes can loosen over time and begin leaking.