If it's a friend I'll tell them why I don't like the game and let them make their own decision whether or not it's a deal breaker. I talked a friend out of my Raven even though I offered it up for $300.
I won't tell someone I don't know (i.e. CL) how I feel about it. I'll assume they know what they're getting into. And if they're a n00b they probably wouldn't discriminate between a good game and a bad game anyway. They'd enjoy it all the same.
Spectrum is a game I couldn't unload quick enough. But it's one of those you can't talk someone out of -- they need to experience it for themselves.