I don't know if this is an already known exploit, but I figured I'd post it here since I didn't know about it until I discovered it, and no one on my friends list knew about it.
http://youtu.be/qBXQwmazf-o
Basically it involves toggling your interp from a low value to the max value. I wrote a script that changes it from .033 to .5. This causes player models to pause for half a second. The result is easy headshots as you can see from the video.
Here's the script I was using in the video:
bind "mouse3" "interpswitch1"
alias interpswitch1 "cl_interp .5; bind mouse3 interpswitch2"
alias interpswitch2 "cl_interp .033; bind mouse3 interpswitch1"
I'm sure that it could be done easier with a bindtoggle, but I was too lazy to look up the correct syntax at the time so I improvised with some of my text spam scripts.
When I first discovered it my initial reaction was to tell no one and keep it my dirty little secret. Unfortunately for me it shows up in pov demos. I figured that if someone found out, a shitstorm would likely blow up over it, so I'm letting the community know about it.
I've only been using it for the past week or so in pubs and a couple UGC scrims.
Here's some back story on how I discovered it.
Months ago there was a thread I found on SPUF where a guy was playing around with interp settings and found out that setting the interp to its maximum of .5 made hit detection much better, especially for sniping. A friend and I tried it out for a while in a 2Fort server and discovered that yeah, hit detection was greatly improved, but since you were 500ms behind the server, you would get killed by things before you even saw them. We eventually gave up on it since the downsides were too great.
I forgot about it until a few weeks ago when I was looking at my different configs. I've been using interp scripts for a long time in my class configs and my crosshair switcher to change my interp settings when I switch weapons. It's only between .0125 for projectile and .033 for hitscan based on what weapon I select. There's no noticeable pause because the values are too low to notice.
I decided that I could make a script that would toggle between .033 and .5 that I could use to increase my hit detection when I was in a safe place and wasn't going to have to worry about being half a second behind the server. Eventually I discovered that the script could make player models pause, and with a little practice was able to really exploit it.
I do believe that this is a hugely unfair advantage, and should be fixed. I just want it to be done in a way that doesn't interfere with small interp changes like the ones I use in my crosshair switcher script.