Stealth is quite broken atm.
- unstealth on aggro (if that's intended, happy to get the patch where it has been changed?)
- mobs not looking at us before aggro
- aggro seems to happen from a long range, but haven't looked at it in depth
That's how it worked back in the day, except for the mobs looking part. There used to be a range where they'd notice something's wrong but most of the time not spot you, indicating it by stopping and turning towards you.
Aggro ranges and everything was pretty crazy for a loooong time. They were decreased over the expansions. Basically a rogue without 5/5 Master of Deception you couldn't sap mobs in dungeons, as they'd pretty much always detect you before sap range. Feral stealth was such a joke even when talented that everyone would always see you at least for a second before you'd get to them, so super twitch dependant. Not talented you'd be spotted from China.
Pets always aggroing stealthed targets miles away is a serious bug though, and doesn't only go for hunter pets..