United's main aim this season is to qualify for the Champions League

Others insist Marouane Fellaini fouled his marker before his goal

Some believe Ander Herrera's goal should not have stood

Here's your guide to working out just how much you hate Manchester United:

If you think Wayne Rooney should have stayed on his feet and let a reckless 6ft 4in, 17-stone goalkeeper shatter his ankle with his wild two-footed lunge then you really do hate Manchester United.

If you're re-writing the offside law claiming Ander Herrera's goal shouldn't have stood, you hate United.

Wayne Rooney touched the ball past Preston goalkeeper Thorsten Stuckman during the FA Cup clash

Rooney went down a moment after and several of the Preston players were unhappy with his actions

Rooney lies down on the ground before the penalty is given by the referee late on at Deepdale

Rooney scored from the spot to put Manchester United 3-1 up against Preston

If you think Marouane Fellaini has fouled his marker before he slams home the second then you hate United.

If you were desperate for Preston to hold on to their lead and felt immense disappointment bordering on physical pain when Herrera, Fellaini and then Rooney scored their goals then you hate Manchester United.

If you are focusing on United not playing fluent football, and completely ignoring the fact that they have lost one game in 19, almost as if you're trying to convince yourself that run isn't true, then you hate United.

If your focus is on Radamel Falcao not playing well then you're borderline obsessed with him, and you hate Manchester United.

Ander Herrera has his shot while Rooney (left) stands in an offside position but does not touch the ball

Herrera runs away in celebration as the referee lets the goal stand while Preston remain unhappy

Herrera scored to make it 1-1 as United went on to win the FA Cup tie and avoid an upset

If you're desperately trying to manufacture more statistics and evidence that show just how much better United were under David Moyes than they are now under Louis van Gaal, then you've got too much time on your hands, and you hate Manchester United.

If the success of your season is based on them going out of the FA Cup and dropping out of the top four rather than anything your own club might do, then you have an irrational hatred of United.

If you've suddenly adopted a philosophy this season that winning a cup tie isn't as important as playing brilliant football during that tie, then you hate United.

If you are focusing on United's negatives after Van Gaal's side made it through yet another away tie then you must be wondering how on earth your team is below United in the Premier League table. And you hate United.

Marouane Fellaini smashes home his goal to make it 2-1 to United en route to their victory

Fellaini scores to give United the lead as they turn the game on its head at Deepdale

Fellaini celebrates as United progressed through the FA Cup tie to the quarter-finals despite an earlier scare

Fellaini and Ashley Young celebrate as United take the lead in the FA Cup tie

If you keep saying United are terrible then you are trying to convince yourself they are terrible. Which is a bit weird. They're not great, but they're not terrible. This also means you hate United.

If you've experienced untold voyeuristic joy since Sir Alex Ferguson left and United fell a third of the way down the table, then you hate Manchester United.

If you are hammering home (to anyone who can't get away from you quick enough) a point about how much money United have spent, thinking that football is played on a computer screen and not on grass, then you hate United.

When a club is as successful as Manchester United have been it's understandable that jealousy kicks in among supporters of lesser clubs, and that transforms itself into hatred.

United manager Louis van Gaal pictured at Deepdale as his side beat Preston to make the quarter-finals

I don't know how United's season will finish, but my opinion is that if they end up outside the top four – even if they improve on last season's seventh place – then Van Gaal has failed. If they win the FA Cup it's a bonus, but United's season isn't about that. It's about getting back into the Champions League.

United want to win the FA Cup of course, but the bigger clubs don't define true success around that competition.

After the calamity of last season, Van Gaal was tasked with rebuilding. Helicoptering in a few expensive signings was only part of the rebuild for a club not used to dealing with failure on the scale they suffered last season.

In simple terms, there is no fear factor with United anymore – that went last season with Moyes' side capitulating regularly. Look at Preston: they were woefully insipid in both legs of their Johnstone's Paint Trophy area final against Walsall recently, and missed the chance to get to Wembley.

Van Gaal applauds at full-time after seeing off Preston as United continued their run in the FA Cup

United are in the FA Cup quarter-finals and are still on course to make the top four in the Premier League

But give them an FA Cup tie against Manchester United and all of a sudden they become a different side. And what about Cambridge United? They put so much effort into that 0-0 draw against Van Gaal's side they haven't won a game since.

I get the tribalism of football, and I totally get that thousands and thousands of fans are absolutely desperate for United's misery to continue.

But I also get that while Van Gaal's United are not going to be remembered as brilliant, he's got them back into the top four.

Whether the Manchester United haters can accept it or not, if the Dutchman keeps United in the top four come the end of the season, he has hit the target most United fans would have set him at the start of the campaign.