It's too much trouble trying to figure out who's tilted and who is not. I found a much better method is to create the tilt yourself. One I do very often is whenever my opponent makes a play that fails and gives me a kill, I would all-chat question marks as if to ask "what the fuck are you doing" or "did you actually think that will work". Sometimes I would simply type "noob". Another one that may work is repeat ganking a lane as a jungler. If the ganks succeed, you can all-chat something like "Are you flaming your jungler yet?"
A more advanced method I use from time to time is sewing discord. Using the repeat gank example, you could all-chat something like "Why isn't your jungler helping you?". If he responds with some remark that exposes his hatred for his jungler, then you know he is tilted. An added bonus is that his response to you will tilt his jungler and has a very high potential of creating a shit storm of petty insults and trolling on the enemy team. Pretty soon their team will implode and it won't be long before they are all report begging in all-chat.