Man, I love the quests - one reason why I find this little game so addicting is these quests. However, it seems that after about 20-30 games the quest system comes to a grinding halt.
I mean, I have about 10 quests opened, but I never seem to get the items needed. The only quest that progresses every now and then is the Motion Twin diet where I miss 9 more cola bottles (and those things aren't exactly common), but the other ones.. nothing. In the last 10 games I didn't see any of the required items even though I travel through at least 80 levels in each game. Not to mention that the last few quests I DID finish unlocked some seriously sub-par items (canned food for instance) which left me wondering if I would've been better off leaving them unfinished.
What's worse, I'm really missing the double-bomb and up-kick abilities on those 80+ levels, but as I hear you need to get some "Book of stars" to even start those quests. As far as I know, getting that Book is just pure random chance and many people never see it even after a year of playing. Great.