Co teachers VS. Sub

I don't know why some Co Teachers of a classroom can't take advice from a Sub Teacher I find it funny and insensitive or why do they feel the need to talk down to sub teachers as if our job entails being your shadow. I say this because funniest thing Ive been noticing I walk in a classroom theres the teacher I usually walk in sit down and wait for the children to walk in but before I can get my mind together the other teacher is giving me instruction to do this and do that to the point I have to ask what there job title is It gets really annoying.