The few of mine are IC most of the time. I may have broken the rule a rare few times for very valuable posts (though my character would probably like it just because it's actually valuable even if in disagreement) but...
To begin with, I was strongly opposed to that like system when they introduced the new forums, and my first rule was never to give any likes. I eventually get to give a few because I felt terrible for not returning the favour to people giving me likes, and that posted things that my character would give likes for.
@Lou : there is that yes, but they are obvious. Someone only posting on the IGS rarely gets above 1000-1500 likes. There is also the fact that some characters get ludicrous amounts of likes due to their circles and friendly groups, or get massive likes dumps from their corpmates. Honestly, I would like not to take much note of that system, but when I enter a discussion where I see constantly the other side getting like 3+ likes per post when I rarely get a single one, is rather depressing in itself (I can count on the digits of a single hands the posts where I managed to get above 3 likes). That system is used as a tool for people to support or blatantly go in the way to "win the thread" without actually bothering to post anything of note to actually support someone point of view. Of course though, I would be even less happy with people empty quoting or just saying that insufferable "this, so much this"...
Most of the time though, I try to acknowledge with an answer a post my character finds valuable, even if there is not much to add.