I can say this: I never had a problem with uninstalling a browser toolbar, or restoring the default search engine in the browser. What I always have problems with, is getting rid of AV software itself. Oh God, how hard it is sometimes.
Norton AV taking half an hour to uninstall is a known thing; I'm convinced they actually have some Sleep() calls in their code just to piss people off. But just last week I tried to get rid of Comodo AV (+ 2 bullshit pieces of software it installed) on my neighbour's computer. Took a while. The uninstaller didn't work (it reported "an error" and gave up), so ultimately I had to resort to manually deleting stuff until the uninstaller finally unlocked itself and cleaned up the rest.
I've been having similar experiences with all AV software in past few years. They're a menace.
Far worse are the lengths that a company like AVG will go to to get and keep their software installed on your computer. Their browser toolbars essentially take all the dirty tricks they've apparently learned dealing with malware to.. build a piece of malware. Honestly whether it's active malice, incompetence, or lack of motivation I don't know, but I do know I've spent hours trying to extract their stuff from people's browsers. (I should say here that I fully expect someone reading this has managed to uninstall an AVG toolbar with no issues. They have multiple different auxiliary tools to their antivirus, and I'm not sure specifically which one(s) caused me trouble personally. It's also likely that they're only a _real_ pain in certain circumstances. But regardless, if you google something like 'how uninstall avg' or 'avg malware' I'm sure you'll find many more examples.)