Neutering cant physically stop cats spraying, the few botched spays iv heard about leave the queens showing signs of heat but none sprayed with it! Incomplete neuterings are pretty unusual, a stressed cat for whatever reason will spray as it feels it has a point to make, i believe that spraying is much more likely to be caused by a behavioural factor rather than a piece of missed tissue.
Simon rarely marked the garden until he had beef with dexter, he now has several spots he regularly pees on, i expect he will stop when dexter goes
Tail quivering so im told is a sign of excitement/anticipation so getting a quivery cat at food time is no surprise
I expect the same tail movement happens when emptying their bladders upright is down to muscle movements in squeezing it out
