Hi,
One of the big things I can think of is that Muslims normally illustrate Islam or their points in major debates in social opposites, and many times in order to glorify Islam in the face of its opposite.
for example: that the Islamic scripture is infallible but the other major scriptures are corrupted, the virtues of Islam against an immoral west, etc.
Like Madhuri, I think the disappointment is that many of us are opened enough to communicate every day with other cultures, we are even opened enough to happily study their religion or theology, but when we discuss these things with Muslims we know we are headed towards a brick wall, and that all our sound arguments, supported by natural sciences or by good intentions are going to be exhausted.
Its a bit disappointing, that you take the time to read someone's scripture, study their religion and history, and not get that in return. its also disappointing that you want to keep up to date with modern science and philosophy, but many arguments which involve Islam seem to expect you to simply shrug off whatever scientific or philosophical understanding you have acquired through the years.
its as if many of us have a knee jerk reaction to expect misconceptions or antagonising in political, social, or religious issues when debating Muslims.
To capture what I am trying to illustrate:
Many here do their best to be opened towards discussion with Muslims and about Islam in general, we do our best to see beyond stereotypes, but get the sense that no matter how far we will reach for the most culturally positive aspects in Islam, we will have the nagging feeling that many Muslims will do their best to form Orientalist prejudices in our brains against our will.