The corruption in Portugal is overwhelming. Sure, there are other countries as bad or worse than our's, but I prefer to put the standards high. You can't compare the corruption in Portugal with the corruption in the UK. There was a study that was made about Portugal that said that if we had no corruption, we would be living with the same quality standards as Finland. When you see the difference between Portugal and Finland, it's realy scary.
Anyway, regarding your question, because of the above reasons people in Portugal should have changed their vote. But they don't.
To give you an example, in the most educated part of our country the people vote for a guy (for mayor) who is clearly corrupt and has already been condemned by justice to jail due to corruption. What's the people's reasoning? "Oh he steals, but he gets things done."
Now imagine how much the others steal to not even geting things done.