This wasn’t a very serious comment, but now I feel like fighting you on this.

Mammals may have evolved from scaly animals too

Not directly, early therapsids had naked skin. Some earlier synapsids had scales, but it’s unkown if it was a general thing or something that evolved independently in a few lineages. You gotta go back almost as far as fishes for something that was definitely a mammal ancestor and that we’re sure had scales.

some mammals still have scale-like structures (pangolin, some rodents)

Pangolins are scaly tho. As for rodents, only the tail is scaly, so you don’t typically call the whole beast scaly.

Should we also call furries scalies?

It’d be strange to apply it to all furries when only a minority of mammals have scales.

No, hair and feathers are distinct structures from scales.

They all share a common basis (and with teeth as well), but feathers are arguably closer to reptilian scales:

• They’re formed of beta-keratin, like the scales of other reptiles and unlike hair which is made of alpha-keratin.

• Both are attested in dinosaurs, some had both feathers and non-feather scales.

Basically, feathers are directly modified scales. Hair appeared from scaleless creatures, altho it did use a gene that had been involved in making scales in this scaleless creature’s distant ancestors.

You could make a point that bird furries could be called “featheries”, which would be more precise and accurate than " scalies". However in absence of this term (which has been proposed several times bug never really enterered general use, “scaly” is more accurate than “furry”.

Tomato

Irrelevant.