Giving mental disadvantages as results of behaviour?

[Vodrilus]

How does the hivemind feel about GM's dishing out mental disadvantages to PC's due to extremely consistent role-play throughout a campaign?

For a bit of context, I've been running a campaign of hard-ish science fiction for a while now, and one particular PC has a very consistent track record of killing everybody he could plausibly kill without breaking the law (or, in other words, being a murder hobo). Somehow, this has been mostly OK with the rest of the party. I've been toying with the ide of dishing out Bloodlust [-5] to this PC to reflect his growing eagerness to kill.

I'm mostly running on Basic Set, with Spaceships and a little Space. Are there supplements already for this kind of thing?

I won't, of course, require anyone else to judge the fun/engagement-factor in this specific instance of the problem, as I'm probably far better suited to handle the situation due to actually knowing my players. I would much rather hear more general, theoretical remarks, or perhaps your own experiences.