I'm sure everyone's experienced an engaging, hard-fought back-and-forth over a keep suddenly come to an end half an hour after inner was last breached due to some Deadeye or Mesmer hiding away in some corner. This is clearly unhealthy, but the tools we've been given to deal with it are woefully inadequate.
A handful of specs have hard counters, but you'd need a legion of them to actually tag the target...and if it's a Deadeye, you have to tag it multiple times in a short period. There are traps, but they're about as useful as a toothbrush made out of a cactus. So the reality is that dozens of defenders are left to scour a keep and try to lay eyes on the creature. They must carry this on ad infinitum or all of their effort will be nulled. This is not fun.
As you may have guessed, I just had an Osprey's Palace flip out of the blue to this. We had been defending it for over an hour, with constant attacks and plenty of roaming action around the surrounding camps. It was WvW at its best. They had breached Inner a couple of times early on and each time we swept every nook and cranny for DEs and Mesmers. We managed to kill a few, but one can never be sure that they're all dead. Right before the flip, two groups were hitting the same south wall with catapults in different locations and we had a pretty exciting multi-level fight where we were outnumbered, but still managed to kill the catas and a few of the enemies. They did serious damage that we couldn't easily repair as there were roaming groups choking our supply lines, so while we won the fight, they also had something to brag about. The constant action seemed to draw people out of the woodwork. We had more people on the BL than we've had since Reset, plenty of communication in map chat and allies willing and ready to respond to all manner of call-outs...but with the stolen cap, all of that momentum soured. I doubt it was much fun for the other server either, beyond a brief moment of schadenfreude.
So, while WvW clearly has myriad problems, I'm confused as to why this one is getting worse instead of better. We get enemies marked after a cap, new traps to mark enemies and the dubious Sniff skill on Warclaw as if that's supposed to turn this into 'engaging gameplay.' That's never going to work, especially against Deadeye...it's just adding layers of bandages onto a festering wound. Does Anet want this to be a thing or not?