Merit abuse is when you send smerits to your alt accounts, or you trade merits for BTC or any other type of payment option, i do not consider sending a big number of smerits to a member as merit abuse because Theymos said:
If they complain about amounts, tell them to complain to me.
Not earning merits and seeing other users earn them doesn't make it merit abuse just because it is not in your favor then, it may be happening for many reasons, post quality aside, this quote from Pmalek seems to be the main reason why member's may not get merits from merit sources and member's that aren't merit sources, you are not showing up in topics that interest them:
I can't speak for others, so I can only talk about my own distribution. It's very simple. I send merits to people who write quality posts in the topics I am interested in. Wherever I read and post at that moment is where my source merits go. The thing is, if the same people keep showing up in the same threads, it's only logical they have a bigger chance to be on the receiving end than those that don't.
If you want to get merited, show up. That's the first thing. Do we have to drag you out and force you to post so we can merit you?
These threads help to make it easier if you are not showing up in topics that interest merit sources as it takes your post directly to them:
https://bitcointalk.org/index.php?topic=5410264.0https://bitcointalk.org/index.php?topic=5093271.0https://bitcointalk.org/index.php?topic=5412657.0