1: You would never ever visit Paris even though the city has a phenomenal offer of sights that would keep you excited for weeks, because the only zoo they have is that pity of the Menagerie (I've never been to Paris Menagerie nor the city itself, so I don't have any opinion, but it doesn't seem to very well-liked around these parts). On the other hand, you would spend two weeks in an obscure corner of Germany with no attractions for the regular tourist other than a small viewing tower because it is packed with nice zoos.
2: No matter the amount, you know which zoos you have visited.
3: You've visited more zoos than a regular person would think existed in the whole wide world, but you barely feel you have seen the tip of the iceberg and have a least 100 more zoos you would like to see.
4: You don't feel embarrassed by visiting zoos without company (not saying you should, but some families might think you would be, being a grown-up walking around in a supposedly kid's place on your own), and you are actually scared of the thought of company who would not realize how amazingly awesome it is seeing that northern white rhinoceros, but instead goes crazy about the cute and playful ring-tailed lemurs.
Guilty in the second one and partially guilty in the fourth one in that if I'm visiting with someone that is at least more than average knowledgeable about animals, I prefer visiting with company, but I'd rather go alone than with someone who thinks a ring-tailed lemur is a sloth.
Mostly not guilty in the first one, though a nice zoo certainly could make the place more attractive to me. Actually I've also tried the third one once, even though I've only visited 50-60 something zoos (and that's counting aquaria, farm zoos and the sort).