Just had one of those coming back from Istanbul-Luton on Thursday, off duty cabin staff sat at the end of a row and told everyone she was waiting for someone, unfortunately for her the a/c was full so in the end she had to relent and let someone sit there and carried on as though nothing was wrong.
Have had a similar problem flying from MAN this year when people sit in the aisle seats and leave the window empty in the hope that they can spread out when the door closes. Bring back allocated seats the scrums are ridiculous.