I wonder what percentage of users are generally fake and how much some startups goose this number. Maybe adding in 5% worth of fake users increases an acquisition price. I'd imagine it varies by the type of app (CRM, social, etc) but that you'd probably have to get your next funding from the Salvation Army if/when you get caught.
CEOs have been invited to conferences to speak about their "sudden rapid growth." They never admit they are cheating. You can usually tell who does it because their traffic will abruptly stop once they realize the 100,000 one-time-login users in Singapore aren't virally spreading or clicking on ads.