Anyone know if it's fine under blizzard's ToS to have a horde and an alliance toon on different accounts on a pvp server?

[KvdM]

We've had folks on Mag since the beginning (or nearly) with "spy" accounts in alliance there. There was also an alliance druid that had a horde spy account and would use him to track lowbie zerg groups and harass us. Neither ever got banned for it.

I know of at least one member of this community that asked a gm about whether he was allowed to use a spy to target specific players. He got warned that he could get banned for it, becuase it is considered harassment under some circumstances. Here's a link to the pvp realm policy:

"The Ongoing Harassment policy does not apply on the PvP server when there is a PvP resolution available. Characters have the ability to deal with their conflicts through combat and Game Masters will only involve themselves in extreme circumstances."

http://www.wow-europe.com/en/policy/pvp.html

This specific player wanted to use eve-style pvp against a small group of other players and that apparently qualifies as an extreme circumstance. So although you're allowed to use a spy and target specific players, just make sure that you don't take it too far.