Researchers created 300 fake identities, signed them up on 185 legit sites, then tracked how much the sites used signup PII to pester the accounts. They tracked how many email messages, phone calls, text messages and other responses were received based on the personally identifiable information (PII) used to register. On average, signing up for a website creates responses resulting in an hour of wasted time due to distractions and some websites created up to 20 hours of distraction. Facebook detected six of eight fake accounts right off the bat and detected the other two within a week.
Source: https://threatpost.com/im-calling-about-your-car-warranty-aka-pii-hijinx/168375/