I'm seeing some leeches or slugs in my bathroom and I want to know if they (leeches) climb walls
I don’t see why not, slugs do.
a photo would show what you've got there.
It's usually centipedes in my bathroom, along with assorted spiders
Are the spiders getting bigger, I had a whopper the other night, I wouldnt pick it up!
They're not likely to be leeches, since they live in ponds and rivers.