I find the tactic,
if you will, rewarding. If you manage to sneak away/flee to a teleporter without dying, you're granted a good spot to pick off the BLUs one by one. It doesn't take much to kill a spy, and they're moderately fast. From how I see it, the BLUs paid no attention and let the spy off the hook if they allow him to make his way to the teleporter. BLUs would then have to enter, since the warden tells them to hunt down for rebels, knowing they’re going to die and regretting that they weren’t able to catch the spy sooner. Correct me if I'm wrong, but I was the first few individuals that discovered the particular strategy. Eventually it caught on with everyone else, and people who were competent on BLU would often go to the teleporter I usually make my escape to.
However, camping the teleporter doesn't always work in everyone's favor. One step too far can land you exiting the teleporter, make you miss your target going through, or getting stuck with the BLU and butterknifing them to their death. Basically, you just have to find a sweet spot.
You can easily counter spies heading to teleporter by:
- Having a medic on BLU that ubers a guard before heading into the teleporter
- The uber lasts for a good second or two, allowing the BLU to turn around and hopefully eliminating the rebellious spy
- Forcing the warden to go through since they have backstab protection
- Immediately running through
- Sometimes the spy swings their melee right before you enter, essentially failing to backstab within the small time frame given to kill the BLU
- However, the downside to this is that it's based on luck
- Having the razorback equipped when playing as sniper because backstab protection
- Firing at your feet as a soldier; it sometimes fling the spy out of the teleporter
Or, like I said earlier, camping the teleporter before the spy plans to.