I'd encourage you to check out Counter-Strike servers which are NOT VAC-secure. Or, well... I don't know how much these servers exist anymore, with matchmaking being so dominant. But back before CSGO, if you joined a server that didn't have VAC enabled, you would have about a 90% chance of it being unplayable due to speedhacking, spinbots, etc. The other 10% was probably still full of people fine-tuning their use of aimbots, wallhacks, etc.