Actually, users very, very frequently bite at spammers. It’s arduous to the moderation process and contributes to a negative environment on Fluther.
On the other hand, the problem with trolls is that sometimes users will identify someone as a troll. . . who isn’t a troll. At least not by the definition of the word that I am accustomed to (someone who doesn’t care whatsoever about the position they are posting about, but is simply trying to rile up a community for some sick pleasure.)
I am more frustrated by spammers. They come in mass numbers and give the moderators more busy work to complete. We have had very few trolls in the few years that I have been active on Fluther. Also, if you ignore a troll, they’ll typically get bored and move elsewhere. If you ignore a spammer, then your site will be flooded with spam.