Regarding fans changing their votes from week to week ...
For many fans the votes they make on polls reflect their current emotions so it is unfair to label someone who changes their mind (in either direction) a bandwagon fan.
There are always some fans who hold out hope longer or give up faster than others over players, coaches, etc.
When a fan changes their mind it may be temporary or permanent, but part of being a fan is having the choice to decide what you like and don't like at any given time.
I think these polls are interesting because they provide a snapshot of the fan base's opinion on various topics, especially specific players and coaches.
It is less about being right or wrong or defining who are better fans and more about gaining an understanding of how Cowboys fans are feeling at various points throughout the season.