Re: Hey, Iran
So the Ummayads, the Abbasids, the Seljuqs, the Fatimids, the Ilkhans, the Ottomans, the Mughals and a few other, less important or even mentionable islamic dynasties down to the Saudis
Suppose somebody decided to kill every redhead he sees.
Is it logical to say that, hey, it's because he's a Buddhist, so all Buddhists are redhead-killers!
I'm not sure whether any of the dynasties you mentioned were despotic*, but this doesn't necessarily mean that it is Islam which made them despotic.
In a similar vein, one might argue that capitalism is evil simply because America invaded Iraq/Vietnam/whatever.
You can't generalize that a principle is wrong simply because some of its adherents did wrong.
So Islam has basicly been constantly "misrepresented" ever since its inception?
Nah, not really. Some caliphates were quite amazing examples of how Islam should be applied (and how should countries be ruled in general). I'm referring to 'Umar bin Abdul Aziz's caliphate here, whose caliphate is held by tradition to have completely eliminated poverty through rigorous distribution of wealth (Islamic alms or zakat), and to the first four caliphs, known as the Rightly-Guided Caliphs.
And as for those precious few upright true believers who represent the "real" Islam this leaves us with... the Qarmatians maybe???
Already tackled above. As for the Qarmatians, you mean the looting gang which killed hundreds of innocent pilgrims and looted the Kaaba? If we were to look at it with some humor like you did, they could be regarded as militant Social Darwinists instead, advocating the elimination of the weaker "excess" of humanity so that the stronger remainder flourishes.
* A quick Google search shows this source, which says that at least the Ottomans weren't despotic.