It's gotten to the point where I straight up avoid manually directing my Sims' pets to do anything they don't already have the related trait for because it seemingly takes so little for it to get "trained" in as a new trait. (This is especially annoying with Piggy- look, just because I have the pet eat when they're hungry doesn't mean I want them constantly begging for food, drinking out of toilets, getting into mud etc.) If I want new traits trained onto a pet, I'll have Sims scold/praise them as the system is for, but I'd really like actions I direct the pet to do not to have an effect. Is that tunable? I haven't found anything in the GameplayData XMLs for it so far.

I have to agree that the Piggy one in particular is annoying. But do you find it still to be too readily obtained if your pet has the Neat trait and is at least once in a while praised for doing Neat things (such as peeing someplace other than on the floor)? I believe they are supposed to be conflicting traits, or at least I would find it difficult to understand how a pet can have both.

Might your pets also be Geniuses? Seems like that would lend itself to them learning new traits faster, including unwanted ones. But also I think we are supposed to learn from this that eating scraps off the floor should be a treat once in a while, as would successfully begging for food, not everyday things for a pet whom we don't want to have the Piggy trait. Are their pet bowls accessible and being kept full of food for them? Are they being scolded for doing other piggy things, before they manage to pick up the trait?

I haven't really tested it. Piggy doesn't seem to get trained in as easily as some other traits, but I've definitely seen the icon pop up for benign actions, which is why I've been avoiding them. The pet I'm currently playing with isn't a genius- she's a stray my actives befriended and took in, that started with no traits.

She does have a full food bowl around, though.