What it should look like and what to do about it?…
Ok, so iguanas (and other reptiles) poop and pee at the same time. Its the same mess as bird poop, which makes sense since they are closely related in their evolution. Iguanas have no sweat glands, all excess water leave the body with their feces, which can make for some very messy disasters if you allow your iguana to go freely about the house.
The first thing to do is look it over. It should have a substantial brown scat (i.e: “turd”), not stringy, and not any unusual colors. Next to the brown part, there should be a yellow-white goo the consistency of egg-whites and finally a pool of water. If there is not at least some water present, your iguana is probably very dehydrated and you should offer a deep water bowl right away. Put the water in front of the iguana and splash it around so they can see that its there. Iguanas rarely drink water if they have fresh, moist vegetables as the bulk of their diet, dry iguana biscuits are NOT good food for iguanas and should only be offered sparingly.
If you offered your iguana clementines or anything high in fluids, WATCH OUT!! its gonna be messy.
The best way to clean after your iguana is to have a roll of toilet paper handy. I cover the whole mess with it and then let it sit for a few minutes. The paper will soak up all the fluid (add more as needed) making it easy to swipe it all off.
Iguanas love to poop in water, so if you would like to avoid this whole process you could offer them daily baths (mine loves hot showers!) where they will most likely take care of business.
On a related note, if you are trying to potty train your iguana… always immaculately clean after the accident if its in an undesired location. Iguanas like to do it on the same place over and over, so the faintest trace will cause a chain reaction. When you see them looking for a suitable spot, place them where they should go and then do a mediocre job cleaning it, this will help them remember to go there again and again. Once the habit is ingrained, you should clean after them fully.