I've just called someone back, because they left a voicemail asking me to do so. That's it, but I'm not the majority of WGs. Did once have a knocking buttons on phone incident quite a long time ago, but I now am very careful with my handset.
I also will not dial numbers sent to me via email, it has actually meant I've missed some genuine bookings though. Some guys will email to say they will be in the area for the next day or two, without internet access so will I please phone them to arrange an appointment. In the past I've been sent incomplete numbers, numbers with innocent/badly typed typo's and then numbers of mates for either a joke, or as part of a malicious set-up.
On more than one occasion I've had potential clients think I'm being difficult, or mean because I would not phone them upfront.