If a dude spawns into your game right around the corner of the LSC and then heads straight into it... odds are he is a glitcher.
Feel free to empty a clip through his window while he waits for the door to open or if you are mildly skilled snipe them from a tactical position.
It is extremely unlikely that a legit player would do this but remotely possible on very rare occasions.
Statistically, I think it you can be quite certain they are cheating.
Many times I start up GTA online because I have thought of what mod or paint job to add to my main car.
You do seem to know a lot about the mechanics of glitching though.
So if you want to take out a glitcher, just blow yourself up. Easy.
As I said.. "on very rare occassions."
Even more rare when you consider that glitchers spawn up right outside the LSC driveway.
As for your last quip, this glitch is all over these forums and there are a vast amount of you tube videos showing you exactly how it is done.
The OP asked a question and I think that my method of identification is far superior to blowing up everyone with a chrome car so I offered it based on what I know.
As to whether or not I glitch is irrelevant.