The answer to this question will depend on your age. As a teen growing up in the 90s, although I had a few United mates for the most part I saw them as arrogant bullies. I will never forget walking into school the day after they spanked us 5-0, head down and those twats taunted me and the other blues all day.
Several things I remember about that period that fueled the inbuilt hatred I have for that club now:
- the banner
- the 'City's going down like a Russian submarine' chant
- their 'Massive club' chant (Curly Watts as a celebrity fan, tallest floodlights etc)
- my dad kept going on about how much he hated them, and that a rag had ended Colin Bell's career
- ickle Citeh
- biased commentators on MoTD, Barry Davies being the worst
- jokes about 5 past Tracy lasting for about 3 years
- our relegations and their reaction to them
- they would always bang on about how Leeds were their biggest derby and that used to piss me off
- Ferguson getting away with everything eg driving down the hard shoulder because he needed a shit
- Cantona avoiding prison for his assault
- Scholes avoiding red cards every week
- Steve Bruce scoring an important goal 8 minutes into injury time (And all the subsequent Fergie Time incidents)
- a general sense that the dice were loaded in Man United's favour. So many decisions, so many let offs. Their fans would gloat and celebrate while I would traipse past Swales protests outside the Maine Stand. Maybe it was part jealousy, but it was mainly a sense of injustice, of cheats prospering.
I could talk at length about my total hatred of that football club but I will stop now and let someone else have a go.