I have a method for judging what is essentially annoying pop.
To start with, we can safely assume that there will always be sucky pop crap (ie. Nickelback) playing everywhere.
The question then becomes: if this band would get accidentally icepicked and get replaced on the airwaves by some other band, how propably is it that you would like that change?
For example, I like the Backstreet Boys because they take airtime from other boybands, most of which are truly unbelievable scheit.
On the other hand I absolutely hate Metallica these days because their post-Puppet material suck in comparison to just about any other metal you can hear on the radio or in a rock bar (in Finland anyway, luckily in here Nickelback doesn't really qualify as rock
)
I'd still propably rather listen to Metallica than the Backstreet Boys, if I had to make the choice. But that's never really the choice is it?
If you'd want to quantify how much a band sucks, you could do a poll. Like this:
If Nickelback would simply disappear as of right now, do you expect that it would be replaced by something that's a) better b) pretty much the same (My expectation) or c) worse.
Judging by most people's comments, Nickelback is one of those bands that's popular, but wouldn't really be missed. Most propably the bulk of their listeners would just drum their fingers to something else, while those that hate them would propably be relieved for about six months before they start hating the next big thing.
To put it in other words, Nickelback's relevance one way or the other is propably smaller than the length of this post, they're just the flavor of the day, no better or worse than most varieties.