  We propose a model of rumor spreading in which susceptible, but skeptically
oriented individuals may oppose the rumor. Resistance may be implemented either
by skeptical activists trying to convince spreaders to stop their activity,
becoming stiflers or, passively (non-reactive) as a consequence, for example,
of fact-checking. Interestingly, these two mechanisms, when combined, are
similar to the (assumed) spreading of a fictitious zombie outbreak, where
survivors actively target infected people. We analyse the well-mixed
(mean-field) description and obtain the conditions for rumors (zombies) to
spread through the whole population. The results show that when the skepticism
is strong enough, the model predicts the coexistence of two fixed points (such
bistability may be related to polarized situations), with the fate of rumors
depending on the initial exposure to it.
