So why else are the Mullahs hated? Another main factor is corruption and hypocrisy.
The people ruling the society, the Mullahs, are supposed to be the religious scholars and icons of the country. They're supposed to be the most pious, and most honourable people in the country. They're supposed to be a rolemodeal for the rest of the population. Instead, the population view them as the most corrupt of all.
Here are just some of the examples going around. Apparently, one of Khamanei's sons is one of the most notorious playboys in the whole of Tehran. He goes through women like he goes through underwear. Another example is Rafsanjani's daughter (or maybe I've mixed them up and it's Khamanei's daughter and Rafsanjan's son, anyway, you get the point), who is rumoured to be a big opium addict. Now the point here is not that these stories are true, as they might not be, but that most of the population does believe them to be true. Perception, at the end of the day, is what counts.
Another rumour that is believed as good as truth is that for every new batch of Paykans (the Iranian car, the pride and glory of the Iranian automobile industry), Khamenei gets 1000 cars for himself (to sell of course, he'd never be caught in a Paykan). In short, that corruption runs down right to the root of the system. Most people would say that deceased Khomeini himself was a good man at heart that did not steal and abuse the system (even though they would not agree with his ideals), but everyone other than him has been corrupted to the bone.
Naturally, this corruption runs down right through the system. Everything is run through bribes. To open a business, like a decent restaurant, you have to "oil the machine." . As a friend of mine told me, it's not that bad if you're caught by the police, since you just bribe the official and they will let you go (the only case this does not work with is the hardcore religious police (yes there are differenty types of religious police), where bribing is a lottery as some might accept it, while others might not and then treat you even worse). If you want to hold a wedding with alcohol in it, then just bribe the police. Basically, every form of government, whether a petty official or high up, can be bribed, and bribing is in fact the established standard.
Unfortunately, this practice waters down even to the everday man on the street in the form of tips. Everything in Iran works through tips and oiling the wheel, everything. If anyone has been to e.g Egypt, he'll get the feel, but multiply that by five. Someone opens the door for you, he expects a tip. I was once in a car parking, and a guy, unasked, came and started clownishly waving his hand as if to help me park. For that, he expected a tip. You go to an outdoor restaurant and there is a security guard outside in the parking lot, and he'll expect a tip from you "for looking out for your car while he was standing there." The guy was actually all the time sitting in his small cabin, probably sleeping, and the only time he came out of it was when we came back to take the car, for no reason of course, but to take the tip. This was not only expected from foreign tourists, as resident Iranians as well were expected to tip.
The other factor that helps fuel this is the fact that most of Iran's people, compared to us, live in extreme poverty. The average person there makes about $100 a month, which is less than what a free visa labourer in Bahrain makes. Added to this, Tehran is by no means a cheap city, as it is only slightly cheaper than Bahrain.
Of course, bribery and corruption exists in many countries including Bahrain, but comparing the corruption in Iran to Bahrain is like comparing a cat to a lion. Even so, many countries in the world suffer from extreme corruption (Egypt, Bangladesh, Nigeria) so why do the Iranians feel such immense hatred to their government because of it? I think it's mainly because (and this is just me conjecturing) the government is made up of mullas, who are supposed to uphold the many principles of islam of not bribing, stealing, etc, but instead they seem to stand as a rolemodel for bribery and corruption, which unfortunately is made to trickle down through society.