This goes for any cheating software, be it ¤22, ¤advantage, ¤ware, etc. (Censored as to not promote cheating runs.) However, some cheats use overlays that show the name of the cheat on-screen or the values of certain cheats, so those will be easy to detect, obviously. Cheaters could always just bind their jump key to a mouse button that doesn't show up on an overlay and hold that for hops, as well. Some cheats also have hotkeys that you can set that disable certain features like autobhop, so that falling off of ledges is still possible.

To be honest, there's really no way to prove that someone's going
FROM SPAWN
OUT MIDDLE
AND INTO THE SAFEROOM
LIKE A SPEED DEMON
with a script unless they make it really obvious. There's nothing that can be done aside from carefully screening every run, which the mods do a pretty good job at as it is. Nobody really bhops in runs, anyway, because we're all shit at it compared to pros and end up wasting time.

EDIT: op y u delete post fam

mat_hdr_level 0 is a startup option. It switches the game from hdr mode to ldr mode. It effectively brightens l4d2 and makes everything very texture less. It does not require sv_cheats 1. There seems to be some confusion. People are mistaking it for a cheat protected command. It is a startup option. It does not require console in any way.

Left 4 Dead 2