Recently I've been emailing local VCs with accelerator/partner programs (With only "contactus" and no application forms) in order to apply.
The mail was the standard small bit a of background about myself, a paragraph pitch about my start-up and a meeting request where I told them that I can show off a detailed demo of my start-up.
The only reason I don't attach the demo into the email is that it contains intricate info about my webapp including every page involved, the functionality etc. and someone can easily duplicate it without much effort with this info in their hands.
Was it a good or bad idea not to attach the demo in the email?
Note: I realize that for well known ones outside my country that request a demo in their forms I'd probably have to include it.
More information is always better. Put yourself in their shoes. If you knew more about the company, can actually look at the demo, etc., it'd be easier to make up your mind one way or another.
VCs are not in business of stealing anybody's ideas. They're in business of investing into ideas. They might have actually seen your idea pitched already anyways. I doubt they'd even sign an NDA, for the same reason, but not because they want to steal it.
If you think somebody would want to implement yours by looking at it, and it might be really interesting, then VC might be interested for the same reason. Also, don't forget, a minute you release it to public (once it's built), anybody can clone it anyways, so you'd have to compete not protect (unless there is a patent involved).
If you think your demo doesn't align well with what you're going to pitch (not in your case maybe, just an example), then you need to change one or the other. Honesty and transparency is very important. Good investor will be very active with your company, and truth will come out anyways.