We all know that Dumbledore tends to cheat in Harry's favor, giving him loads of points towards the end of the year. We also know that Quidditch scores DO, in some way, factor into the House Point system (though it may not be a simple score = house point scale).
Given that the team who wins the Quidditch Cup tends to win a lot of their games, does it stand to reason that they have a better shot at the cup?
The scores we tend to see for the House Points are in the 300-400 range, and each team can earn at least 150 points from Quidditch games (from the linked score, we can determine they got at least ~50 points from the game Harry won).
This means that fully half of the House Points could come from a single student catching a shiny thing.
Are there canon examples of Houses winning the House Cup but not winning the Quidditch Cup, excepting those where Dumbledore handed out a gagillion points just before the House Cup was awarded?