Same here - I don't write YA either. I just found Ron's coarse language quite surprising. If he was my kid, he'd get such a spanking... lol
Several of my characters are very potty mouthed, and one of my favourite things about writing them is coming up with new slang and obscenities. So, my Egyptian harem girls exclaim oaths like 'Hathor's holy tits!' of 'Nut's cosmic cunt!' - it's fun to make up colourful blasphemy
My MC is of better breeding, and very rarely swears - except when he's been in the company of his brother in law, who is also of earthier stock, and a little coarse mannered. After a few scenes in his company, my MC is effing and jeffing without even knowing it, tee hee
In my WIP the MC and several of his cohorts are rather coarse and have less education than others - so they curse more.