Most of SDN is one of three things:
1) Speculation without evidence
2) Someone's experience
3) Data with analysis
This thread began as #2; it has devolved to largely being #1.
I do agree that the nursing staff have no direct influence on your application; however, they can certainly make your time there pleasant or unpleasant and they can certainly influence the medical staff's opinion of you. It is not unlike how things will likely be as a medical student or resident. Sure, the charge nurse of the ED does not evaluate you on your EM rotation; however, if she keeps having problems with you (including having to deal with staff complaints repeatedly), you can bet she (or, more likely, the clinical manager, nursing director, or medical director) is going to let your supervising attending or resident know what a problem you have been and I would bet that repeated complaints like that could have a substantial impact on your clinical grades. Further, as a physician, your nurses will have a great deal of influence when it comes to things like how often you are called in on any given night. There are many stories of a**hole physicians who get calls for the most mundane technicalities by the night shift when the same staff would have handled the slightly out-of-range v/s or pain themselves and not awoken the resident/attending unnecessarily otherwise. (By these, I am not referring to cases where something is clearly out of range, but to the more "yes, technically a call could be made for clarification, but the doc clearly would not want a call for a patient whose pain was only a 7/10 because I was a dumba** and awoke the sleeping patient to ask her pain" or a BP that is slightly above on one reading but then normal when re-checked. Basically, there are grey area cases where a nurse can sometimes avoid having to wake the attending. If you tick them off, they may take out their frustration on you whenever they get the chance.)