I think it is rude not to ask the person behind if they can recline their seat back! Travelling in CE from Faro the other week the lady in row one kept trying doing so and I kept asking her to put it up a bit in the end the Cabin Crew asked her not to, she was hugely aggressive to me (telling me it was disgusting how people could travel in club when they hadn’t paid I corrected her) but she had been knocking the bubbly back in the lounge and on the plane. The people sitting round us kept telling me how awful she was.