I think any bug (insect or spider) is pretty gross if you see it through a magnifying glass. More so than any mammal or reptile.
That said, what is digusting and not is of course a matter of view point. I'm not sure animals have such feelings as disgust, but if they do, I bet humans are a little disgusting to say, a shark. I've heard they eat humans only by mistake. If they find out it's not a nice seal or some such nice creature with a decent amount of body fat, but instead a bony human, the shark will spit it out.
Btw, have any of you observed the masses of humans during rush hours? It kinda reminds me of ants or bacteria / disease. Also take a look at the mountains of waste we produce, and you get the idea.
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