There was always banter between both sets of fans when I was growing up.
That remained when they were winning just about everything in the 70's, because we had class.
Tensions mounted when the HK bandwagon rolled, until it exploded with that git Dogleash. But despite that, there was still badinage.
Then SAF strolled into town, and TRS hated that. They couldn't handle it. They went into meltdown. All banter was suspended forthwith, in the minds of TRS, and to compensate for hating MUFC more than us, they made it out that the breakdown in banter was solely the fault of the Blues, and came up with the ridiculous title 'bitter' to compensate for this to mask their own deficiencies.
Then, strangely, WE became the bitter ones. This was brought about by THEM not being the top club.
Still, the BLUES gave out banter, and TRS only saw that as jealousy. They accelerated the 'bitter' theme until WE started to defend it.
Cue, funny faces and saying something along the lines of "ok bitters". Or,"five times"
Er, no, I would reply. You won the European cup four times. The Champions League once Four and none do not equal five. Morons.
If that logic were to apply, we won the ECWC which is now part of the Europa League. Therefore, we have won the Europa League.
So the answer is, only your preference of club differentiated us in the sixties.
Their success did not stop our humour in the 70's, so banter was still evident.
Our rise and their stagnation and sodding Dogleash really strained relationships. But still we tried humour.
The MUFC domination in the 90's onward, was just too much for them, so they made us out to be the 'bad guys'.
So, all in all, there is a chasm in class and reasoning among the fans now.
And the above explains it all.