To answer your question, let's think of what they usually do. It often goes something like this:
1. Go to some easily type-able URL and download a remote desktop-ish app
2. You give them the PIN, they take control of your cursor and keyboard
3. They open command and run "tree C:\" and *while the output is scrolling by*, they type a message that appears at the end of the output saying "xxx number of viruses detected"
4. They then offer their services for a "small" fee to remove the viruses