I don't like TS3 ghosts... I mean, they look pretty and everything but you can interact with them the same way you interact with a living Sim. I would like it better if you couldn't do anything like Hug, Kiss, etc, anything that involves touching them (that sounds a little perverted, oh well). I would prefer the interactions be like "Talk To Ghost", "Ask About Death", "Make Fun", etc.
Depending on their traits, they may or may not talk about it... But yeah, that would be a good interaction for if they didn't. If they were like charismatic/friendly/etc. they might go off into this long exaggerated story with hand motions and stuff.
I don't mind the ability to touch them, mostly because I love making ghost babies, but I do think there should be more ghost specific interactions beyond the involuntary ones. I like how some uncontrolled ones act out aspects of their death; starvation ghosts are always hungry, fire ghosts always need to shower, and drowned ghosts are always tired.
That would be cool if you could discuss with them about their death.
I'll confess, I kind of have a 'fear' of ghosts. I've had it since The Sims 2. Now, I know The Sims 3 ghosts aren't as scary as The Sims 2 (well at least they can't scare your Sim to death). Still every time I see one I flinch or my heart jumps a mile. Dunno what is about them. I hate going near the grave yard, and in reality I hang out at grave yards all the time. So I don't know what my problem is in the Sims. XD