http://www.youtube.com/watch?v=43jxIaL0pLA
The thing with polls is that they're always based on reputation, earned or unearned. The Tenth Planet? It's a great debut for the Cybermen and has the shock of the first ever regeneration, but peel the layers and it's pretty damn generic. The Tomb of the Cybermen? It's quintessential Doctor Who, but that doesn't mean it's a classic. The Web of Fear? Great story, but in a season with only one story being the odd one out, it's Base Under Siege™ to the Nth degree.
When I started on the Sixth Doctor 6 months ago, I was aware of The Twin Dilemma's awful reputation, and I think much of that is justified, but it's not the worst ever, and Colin Baker still made it worthwhile. And since I've railed on polls, here's another ranking list that's a load of doo doo.