The last of these is something we've not seen occur anywhere other than CoX with quite the same ferocity. In CoX, a game where teaming is encouraged, a 'blind invite' is an invitation to join a team that's sent without any warning. There's no indication of what the team is going to be doing, nor of the level or AT of the person doing the inviting. It's just a box that appears in the middle of your screen, asking you if you want to team or not. Why bring it up? Because if you're new to CoX or haven't been playing long, you might not be aware just how much resentment there is over this issue.
Inviting people to team with a single click and no other interaction is a quick and easy way to assemble a team on the fly. However, many players also see it as rude and intrusive, the equivalent of any other kind of unsolicited invitation in life - such as an invitation to change your electricity supplier, for example, or to take a free personality test. In addition, when L33TBL4ST3R sends you an invite, the dialog box asking if you want to team with L33TBL4ST3R pops up by default in the centre of your screen. This can be more than a little inconvenient when you are surrounded by Supa Trolls, Clockwork, Devouring Earth or any other enemy.
Some time has passed since the Developers addressed the teaming interface. They gave players the ability to add comments to their search windows, such as 'No farm teams', 'lookin for xp', and 'No blind invites on penalty of being stabbed in the face.' These were largely ignored, so the ability to flag yourself as actively 'looking for team' was added, as was the ability to block any and all invites. The blind invite haters were at last able to game undisturbed, albeit at the expense of having to adjust their settings if they ever wanted to accept a desired invitation.
These days, most blind invite haters include a short message in their comment field that reads 'Send tell first', or something of that ilk. To the pro-blind-invite camp, sending a tell first is a pointless waste of time: they want to get their team together ASAP, and they shouldn't have to bother with what they see as trivial courtesies. When this group encounters the anti-blind-invite crowd, which happens more often than you might think, sparks fly.