For ally, it seems to be x-roads, and for horde Goldshire and Westfalls
There weren't so many I saw who would do something like raid Thunderbluff, as several from my then guild did. But the real truth was when x-realm BGs first came out, and on a newer realm where the gates of AQ were just opened, nad few were there; facing tier 3 horde on old realms was, umm, well... They wouldn't even fight us seriously. Doing things like dropping the flag in WSG to do nothing but laugh and /spit on us, when all they could have seen at that point was our gear, was the size of it. It took 15 of us in a pre-made, all coordinating on vent to take one of these people down. Our gear ranged from mere greens, to dungeon set 1 at best. We had to bust tail like it was the most difficult raid boss to take one down.
At that, they stopped laughing, and just ganked the living hell outa us the rest of the time; but it was obvious they weren't even trying to fight for real.
Anyhow, several had enough, so decided to world PvP, and take it out on the horde on our realm. It ended with global (paly) stun locking them, Bain (priest) mind controlling them off the cliff, and me at bottom sometimes 1 hitting them on the off chance they sometimes survived. We musta got that 60 tauren druid like 15 times in a row, and the warrior 12
We did it for 3.5 hours until a raid to take us down was organized, and felt a hell of a lot better about the then brand new cross realm BGs.
But speaking of lvl 70s, look at the alliance of late in AV. They used to win it. Then when AFKers got dumped, the horde coudln't AFK. So now the horde wins all the time. More then a few games people stand around saying "we'll lose anyhow so why try", or we'll stand at "the o" at the end, and no one will pull as people debate whether we can win. Some won't tank, and the healers get popped off one by one. Then again, some fugure the DPS can just hold the mobs.
My hunter used to be BM, but is now a raiding spec, as I'm running kara and Gruul's. Fat chance of my pet holding one of those bosses in the various towers and lasting more then a coupel secs. On the other hand, when the BG ends, I'm typicially over 100,000 (more liek 135-140k) damage, not that high a percentage at that damage or higher. Having the xbow from Attumen the Huntsman among some other epics helps though...