Oh yes, One of my bug bears, the sitting at the aisle with luggage/bags/coat at the window seat.
I have seen on a number of occasions, passengers, usually of the female variety, sitting at a four seat table, hogging all the seats and placing a handbag on the seat opposite them as well indicating a falsehood that the seat is occupied by another passenger who might be paying a visit to the toilet or some other activity, thus preventing others from disturbing their space.
The problem is, hardly anyone challenges these people about it, and even more frustratingly, neither do the train crew.
Personally, if I'm on a long journey, say Cornwall to London or (hardly possible these day) beyond Bristol, I have a shopping bag which I place what I need for the long journey and place it under my seat. It's a little problematic when the seat next to me has been taken, but I'll manage.
As regards feet on seats, well, horsewhipping without mercy sounds a little too lenient to me. Amputation without anaesthetic would be a more apposite remedy.