the worst one i've been to, and sadly the first one i went to... my first ultrasound for a breast lump was five days after i had turned 18 and they threw a fit about my mom coming in the room with me, we almost had to walk out.
another time i went in for an mri of my hip and pelvis, and they said they couldnt make heads or tails of my order. "we don't know if you are getting an mri of your hip or of your pelvis, your doctor didn't specify" were the exact words said to me. they turned me away and said to come back when i'd sorted it out. when i called my doctor she said it states on the order that she wanted an mri of BOTH. ridiculous. ended up going to another location.
haven't been back since, thank god.