They always seemed to be screaming 'Exterminate!', but I don't remember seeing them actually exterminate anyone that often - Least of all, The Doctor!
Perhaps they were just shouting the E-word to get attention, maybe they're just 'misunderstood'....
Seriously though, I was genuinely sorry to hear of Mary Tamm's passing. Both she and Louise Jameson were, in my humble opinion, the best (and most beautiful) of The Doctor's assistants.
Dr Who and the Daleks!
Re: Mary Tamm
Sounds great those outakes .I recently watched Mary in The Armagedden Factor on VHS found it rather slow going but the acting was good all round