For those who actually tried it, is cold-calling any effective? Because if someone I don't know called me up and tried to sell me "solutions", I wouldn't bother giving him the time of day.
It very much depends - for everyone, I suspect including you, although I could be wrong - on what solution the caller is offering.
There are a truly vast number of "solutions" which people might try to offer me that I'm just not interested in.
However, if someone was to call up and offer me a production-grade finger motion capture solution for under $1000, they'd definitely have my attention. Ditto a procedural solution for creating interiors in a fantasy or medieval setting for use with path tracing renderers. And I could reel off another half-dozen ideas.
That's why Patio11's "talk to them, find out what their problems are" approach is so darn effective - it narrows down to the solutions that will actually capture your interest, because they're solutions to problems you actually have.
(Re finger capture - Yes, I'm aware of the Leap Motion and Control VR. Both are interesting, Control VR slightly more so, but neither are quite production-grade yet.)
Do other people respond differently?