Possible glitches or errors:

[SnooD]

         This IS NOT something that I am just posting for no reason. I have seen some, in what I think to be glitches on DP. I do not have demos for these they are on my other computer's DP which i deleted. I have seen in some matches even public servers' grenades literally going through a player model. I have also noticed while I am holding down on the mouse button (spraying) and someones' name is lit up, right in front of me they do not die. Could it just be me? Or is something off, like a player model hitbox or something of that nature. And yes don't think I'm not waiting for some smartass remark.

[jitspoe]

Grenades going through people and disappearing is a glitch, and I believe it's fixed (but a lot of servers are still running old versions).

Shooting people right in front of you is, ironically, probably the most difficult time to shoot them, since the distance they move on screen is the greatest.  Several people have posted "nodie" videos, but they've always been a perception issue.  I'm not sure what happened in your case.  The only case I know of where you can shoot through people is when 2 players spawn in the same location.

[SnooD]

yeah I noticed the spawning in the same location a few years back, well thanks. maybe it's just me.

[Foxhound]

snood... if you see someones name all that means is your cross hair moved over that player... Just because you see them doesn't mean you will hit them.. for instance, while lining there is a gap between the balls in which a player can slip through if they are lucky, also if the player is really far away the balls will drop while your cross hair stays in the middle, and also if they are moving sideways... don't aim at them you need to lead them... newb.

You're not the first person to cry about seeing a name and they don't die, these people are idiots who don't use common sense.