That was why I stopped flying with QF and went to NZ. Had a nice exit row aisle seat ..was all settled for LAX-SYD. Got told they had a passenger "with a seating problem" and ended up with a behemoth of a man in the middle seat (his tiny wife in the window seat???) He flowed over the armrest convincingly...at which point I discovered MY armrest was broken.... No way I could sit like that for 14 hours. When I talked to the CC they could only offer me a Bulkhead seat (I know some folks like them...I don't)
If I had known then what I know now I would have said "fine..put him in the exit row..but I'm getting off...and I'll have my bags please"..... I didn't realise THEN they were breaking their own rules.... this guy could barely stand up without assistance... irritating situation all round.... Why didn't they just bump him up?