Original source for this guide is Russian "It's A Secret To Everybody" group in VK, and all rights for this information belongs to them. I've just translated this page so more English speaking people would know about this.

One way to fight lagbots is stay on the server longer than the 25 seconds. Usually, lagbоts automatically disconnects from the game within 25 seconds. To stay on the server more than 25 seconds after its crash, you can enter this command in console: "cl_timeout 1000". Now you wouldn't disconnect after 25 seconds like others do. When lagbоt will leave the server, you would stay and the server would work normally.

Second, before votekicking the lagbоt, you should warn everyone to enter said command AND also press F1 immediately after vote starts. If at least 2 people will vote for kick, then lagbоt would be kicked successfully.

Don't put a "Cheating" or "No reason given" in the Kick reason tab. Somehow lagbоt needs more time to react when people are trying to kick it for other reasons.

[06.04.2020] This no longer works due to how lagbots instantly crash the servers. They even don't allow you to connect, so if your loading bar stops on 2 or 3 bars (which means there are lagbots in this server), leave the server.