lol who would want either of those shitty add-ons to begin with? Most ppl i know who use FF have a selected handful of add-ons which they always use/trust and only add new ones if they hear a ton of positive opinions about them and actually need the added functionality that they offer.
Anyways, this is the inherent drawback to having a program compatible with user-made add-ons, you run the risk of the creators of the add-ons being total malware asshats. Much better than IE and Chrome still though, in stability, security and usability.
I clean infected PCs every day at work and there are countless, horribly infected computers with IE or Chrome as the default browser, but the number of horribly infected computers i've cleaned with FF as the default in the past 6 months, i could probably count on one hand.
I install FF with adblock on the PCs i repair, and some ppl just refuse to switch from IE, why i have no idea, but they end up coming back in a few months. It also doesn't help matters that ppl still think that just because their PCs came with norton/mcafee installed on them that they'll actually have active (or even passive) protection against malware and such. Eset/NOD32 with spybot+teatimer (set for auto nightly updates/scans) has been the only combination of protection software that I've found to protect these customers from their own poor browsing habits (btw, malwarebytes pro has failed to detect/block numerous things that SB does). A bit of an off topic rant, but i'm waiting for this spybot scan to finish anyways lol.