I will say this, and I know it's going to come as a surprise to some, but I think it's important to say.
Some of these 'irritations' that are sometimes brought up in this thread are things that I view as a bit over-exaggerated.
For example, if a person misidentifies an animal when the sign is literally in front of their face, yes I see them as annoying (unless the person can't read or can't read the language in which the sign is in). However, I cannot get the issue when a person misidentifies an animal when the sign isn't in their direct vision. Sure, some animals like tigers are very easy to identify. However, I think misidentifying the exact species of an animal when the sign isn't in their direct vision is understandable. Maybe they just didn't want to go through the hassle of finding the sign, maybe they just made a mistake or maybe they aren't that knowledgeable on animals themselves, and are coming to the zoo to try and gain more knowledge. In the latter point, I could argue that they should then search for the sign, but I don't see it that way. If that visitor can't see the sign clearly, or the sign isn't in a clear location, then I see it as excusable.
Another example is with toddlers. I understand the annoyance when toddlers bang on the glass, scream, touch/feed the animals etc. when the parents don't interfere. However, some of the stuff toddlers do (e.g. running around, skipping some exhibits, not read signs etc.) isn't an annoyance for me, because they are toddlers. That's just what toddlers/children do, and we can't fault them or the parents for it. Hell, when I was a toddler I probably ran around, skipped exhibits, and I certainly didn't read signs. I just wanted to have a fun time, and most of the time, I did. Toddlers are drawn to the 'big ticket' animals in zoos (giraffes, gorillas, lions, tigers, bears etc.), so I don't see why people get irritated when toddlers don't look at insects, reptiles, amphibians etc. because most toddlers just aren't interested in those things. Hell, I usually skip the insects and I'm not even a kid, I just find insects boring and I would prefer to just look at everything else. Does that make me an irritating visitor? I would say no, because I don't want to look at the insects since I find them boring and I have a (admittedly, irrational) fear of most insects. If a visitor doesn't want to look at a certain animal, I can't see what is irritating about that. It's their personal choice, so I don't see the point in getting angry about it.