It would be like subscribing to political blogs on $rssApp and then leaving bad ratings for the app because your news stream is filled with political news.
Facebook's tools have been pretty good so far from blocking spam from friends. Games (the main offenders) can be outright hidden or blocked, noisy or shitposting friends can be turned down to manageable levels (updates -> only important) or hidden outright.
Really the best thing they could add for flexibility is a keyword filter...
So i'll say it again. You, the user, is ultimately responsible for what comes up in your stream.