Well, just a bit ago, I figured out my basic standards for grouping up.
Player A, who I'd worked with before, asks me if I want to run Blackrock Depths again tonight. Politely turn him down as I was about to log, but would have joined otherwise.
Player B randomly messages me out of the blue with "hay cn u tnk for brd plz"
My reply to him was much less courteous, and involved denouncing his lack of an attempt at typing anything in English.
Guess which one, had I been interested in another run tonight, I would have helped?