I think the lack of centralized Islamic belief structure is quite hurting public perception of the religion. It is completely impossible to say which interpretation of the Qu'ran is correct when there are major differences everywhere and every branch claims the same. There are even differences on seemingly simple stuff like the day Ramadan starts. There is not a single authority that speaks for the entire religion. There is no Pope, there is no Dalai Lama that could be considered worldwide authorities on their religion.
That becomes problematic when you look at news broadcasts. For me personally, I remember Boko Haram, Al-Qaeda, Muslim Brotherhood, Mujahideen, Taliban, Al-Shabaab, Ansar al-Sharia, Hezbollah, Sharia 4 Belgium, al-Aqsa Martyr's Brigade and Hamas. These are muslim terroristic organisations that were mentionned on television in 2014. That is a lot of organisations.
You have some imams denouncing these groups but it is really hard to gather their credentials. What would you say if a random priest from a random country claims that Catholic priests are investigated for sexual acts with kids and that it is just a small minority. It is a lot different if the pope claims that. It is also difficult to know which of these imams can be trusted as at the same time, there are imams under investigation for supporting the earlier terrorist groups. For instance, one of the popular Belgian imams was Iliass Azaouaj, he was killed while fighting in Syria. One of his collegues was suspected of getting young people to join IS.