hah, yeah, my brother has a huge and ever-increasing paper book library, so I regularly "borrow" books by downloading a copy off of torrent sites
And absolutely, the formatting is often very screwy, even if the version you download is an epub (who knows what it was before the user uploaded it), let alone using calibre to convert from something else like lit or mobi. I got so frustrated with it early on (along with the Kobo1's double line spacing) that I wrote up a bash script that cleans up the html and gives me fairly consistent formatting.
With all of that, the only issue I've *ever* run in to is the double-tap, and that hasn't happened often enough for me to either really complain about it, or notice any kind of pattern.