There are impatient, self-centered people in this world. She probably would have waited in line at the grocery store longer than it would have taken to wait for you; you just weren't her priority.
Rack it up to "it takes all kinds"
As for bad transactions.
I have to say (Knock wood) I have not had a bad experience buying anything on Ebay. I have been lucky that all my sellers took extra caution in packaging, were prompt and honest. I have always left 100% positive feedback, and received the same.
Thing is if something is trash or "for parts" as a machine I recently purchased, I will pay accordingly, but was pleasantly surprised that the repairs were minimal to get a great value.