Our internal medicine residents are really good (probably among the top in the nation), but they sometimes have occasional lapses in judgment. I overheard one of the other residents ask an IM resident if he even went to medical school when he said a patient didn't need to be admitted (I won't go into specifics).
It's that kind of thing that doesn't foster a great relationship with other residents. Sure, we all have residents (and attendings) who don't think a patient doesn't need to come in or thinks we should do more in the ED before sending a patient upstairs. When that occurs, I'm usually nice about it. If it's not incredibly busy and it's a reasonable request, I'll do it (usually sending extra labs).
Remember, the toes you step on today might be attached to the arse you kiss tomorrow. I believe in the philosophy of being nice to consultants and admitting residents, and they in turn are usually nice to me.
In my year of internship, I have had only 3 instances of problems with consultants/attendings and residents. One was a surgery resident who was having a bad day and later apologized for saying something that was completely out of line unrelated to patient care, another was from an attending that sent a patient in for a VQ scan without any risk factors, and the third one was one I will always remember. A vascular surgeon who wanted me to "ice" a patient with an expanding neck hematoma after attempting to have a bowel movement. Oh, I forgot to mention he was 3 days out from a carotid endarterectomy. He took a hint and came in to see the patient when my attending called him back to let him know the patient just smoked a tube and would need an ICU bed.