Is it normal for my cats to have super smelly poop??

My cat had the same issue! The remedy to fix this was simple. I bought him quality cat food. You can tell quality by ingredients if the first ingredient is meat product and not corn it's good. I got natural choice from petsmart. It is expensive, but coupons are available and you can use multiple coupons. My cat's poop doesn't stink and he poops less because he absorbs more nutrients from the food. AND he eats a lot less, but loves the food. It's like cat treats to him. Also try not to leave food out all the time

Cat poo isn't exactly the nicest smelling stuff in the world anyway but the quality of the food you are feeding them can have a great effect on what and how much comes out the other end. Like everything there are high quality dry foods and low quality dry foods.
Have a look at the ingredients panel, if it says things like cereals/various cereals, meat and animal derivatives, colours etc etc this normal denotes a poor quality food which doesn't state what the actual ingredients are (or is really vague). Particularly cats whom are obligate carnivores can really show a difference in poo if cereals are listed as the top ingredients in their food, they tend to pass through mostly undigested and means they may poo more.
Try a quality hypoallergenic food and see how you get on.

Maybe they going over other's people house to eat and not eatting the food you put out for them. Means they might be eatting out of trash where people throw out left overs.

It's cat shit. It stinks. ;-)

Sounds to me like you won the lottery or something

I rescued a cat that had that issue before. He stayed outside my apartment for for a week before I realized he was declawed. I took him in a fed him the same thing as my other cats (dry catfood) I kept him for almost 6 months trying to find a home and the condition never got better. I ended up giving him to a shelter because I got so tired of the horrid smell that he ended spending most of his time couped up in a small bathroom. And that didn't seem to responsible of me. The vet said it could have something to do with the condition of the intestines. I never had the time/devotion to switch foods. I was just trying to help the kitty that was thrown outside with no claws to defend itself.

Unfortunately, cat poop does stink. My cats get high-quality cat food, and they still produce the smelliest pee and poo imaginable. It's gross, but I think it's better than going out in freezing cold weather to pick up dog poop.

You can get a covered litterbox to help with the stink problem. It doesn't smell as bad, but some cats won't use it since the smell inside is stronger.