I'd say definitely that arguments are a feature, sadly
We often find that Mil is very 'confrontational' and deliberately provocative - a complete change from pre-dementia. Like Kevin, we can often spot the signs and try to distract - though not always successfully, I admit!
I think that mostly, she seeks out/starts arguments because of frustration at her situation - she gets cross when she struggles to do something, gets cross when she finds she needs help, gets cross at the loss of control and independence - and expressing that frustration by way of causing/starting an argument is her way of 'kicking the cat', so to speak. That frustration is often fuelled by the delusions and confused memories, that often provide her with her justification for the rows, and the whole situation is made worse again by her loss of ability to consider anyone/anything other than herself and what she wants. Its very 'toddler' like, I often think, and trying to reason with her is just like trying to reason with a 3 year old - albeit one who has a pretty good volcabulary and who can be very eloquent, in Mils case!
So, we try to distract, and if that doesn't work we go to 'I'm sorry you feel like that, but I am not prepared to discus it', and walk away. She is very clever at trying to start up the row again, but we try to stick to responding with that exact comment and not to be drawn in - and thats a lot easier to type out than it is to do, I'm afraid, as she can go to extremes to get a response, and I am not always very good at following my own advice