Yes there is a difference. I teach people to work with computers, some are really clever and do amazing things, and some of them have trouble with relatively basic things such as navigating an "Open file ..." dialog window.
None of these people would have any problems grasping the idea of having the options 1) pay $6 and cross the bridge, or 2) don't pay $6 and find another route.
But neither the 7-year old kid, nor the grandmother will be able to figure out how to uninstall this Ask toolbar.
And maybe one Ask toolbar doesn't mess up your computer, but it is one more thing they did not ask for, and those things do add up to a slow and unusable computer.
That sucks. And here's the reason why it in fact is inherently evil: But even then, they did not ask for it, were never in the position to make an informed choice, and do not know how to revert the choice they did not wilfully make. It is preying on the weak.
I have seen cases like am 8 year old kid, who had just obtained his first PC (looked like it used to be a thin client, must've been real cheap, but not in terms of weeks pocket money!), it was infested with crapware, I swear I turned my back for a few moments and saw another toolbar had appeared. Unfortunately, as you probably know, fixing a computer like that takes a whole afternoon, but that's not the job I'm there for (I can make that kind of time to help out my parents occasionally but that's about it). This kid came from a low-income family, his two parents not exactly the brightest when it comes to computers either, so, what now? Breaks my heart, really. Paying someone to clean a computer is expensive, and they don't always do a good job either (or leave some remote desktop tool in place, etc etc).
How is this not evil?
If you want to make a non-computer analogy, how about being tricked into accepting some ridiculously overpriced service in a foreign country where you don't speak the language? Classic tourist con. Those who do speak the language say "No thanks", and walk away wondering what suckers fall for such an obvious trick.