Some people indeed do not read body language, or even obvious clues like the earbuds inserted into place and the magazine in my hands.

On one 5 hours flight the woman next to me initiated conversation. We were both on the same connecting TPAC flight and worried since our incoming was arriving late. After the conversation seemed to run its course and I was settled into my reading/music, she would start talking again. Now, she wasn't trying to convert my religion or sell me anything but this woman did not seem to understand that I couldn't hear her with the earbuds in but she would pepper me with questions since she was a new-ish flyer and lean in and look at me so I couldn't ignore her. I only took out one earbud and kept the magazine on my lap (as a hint), get her to repeat her question, answer it then it would happen again! The saving grace was that this didn't start until the last hour of the flight.

Oh, upon learning we were on the same connecting flight she even suggested we sit together! Thank goodness my prebooked seat was not next to hers.

On the other hand, I had an enjoyable conversation with the other 2 lone passengers in my seat row once. We were all moderately experienced flyers. The conversation was about the current state of air travel and lasted about 30 minutes. After that there seemed to be a tacit understanding that each person wanted to be left to their own activity for the rest of the 90 minute flight.