Explicit statements from the salaf!
Aboo 'Abdillaah Muhammad bin 'Abdillaah al-Andaloosee, Ibn Abee Zamaneen [d.399H]:
"And Ahlus-Sunnah did not cease to degrade and insult the misguided ahlul-ahwaa' and prohibit from sitting in their gatherings, and fearing their fitnah, and informing about their innovation, and they did not see that as gheebah nor slandering of them."
[Saheeh: Al-Khateeb in Al-Kafaayah (pg.52), Aboo Nu'aym in Al-Hilyah (7/152)]