What is the definition of a spam user?
The more I think about it, the more unclear it becomes.
Is it someone who repeatedly posts short replies? But many power users do that too.
To judge whether something is spam, it's certain that we need to look at the account's overall activity, not just individual replies to oneself.
And it's better not to reply solely for the purpose of getting reactions to avoid being labeled as a spam user.
It's important that replies contain some content that you want to convey.

enjoy crypto 🌈 
manga, anime, music, movies
I like exploring new things, so I test and give feedback and introduce them in Japanese.
FID : 17507

I think dwr is half right. Spam is basically a user who is “uninteresting to you”. But there is a smaller subset of people who are literally replying random shit that nothing to do with the original post. 

The reason question is: does the distinction matter / what to do about it?

I agree but I take a different view. I don’t distinguish between these 2 groups because I don’t want to see either in my notifications. However, my main issue is with the power badge being “too powerful”? Every once in a while there are genuine replies and I don’t see them. 

That said, with the current state of things, I’d never turn my priority mode off unfortunately.

yeah, replies that don't match the content of the cast are clear examples of spam.
I agree with you, I'm also concerned about how to distinguish between these.
This is because even among people who claim to be "human", there are indeed those who unconsciously repeat meaningless replies just because they want a power badge.