Ah the joy of roaming profiles where a user has a giant file on his desktop, gets bored waiting for his laptop to sync on shutdown or his battery runs out, and

Ah the joy of roaming profiles where a user has a giant file on his desktop, gets bored waiting for his laptop to sync on shutdown or his battery runs out, and then turns the machine off. What happens to the profile in this situation? I say this because I have had numerous times this happened to a colleague that I had to fix - the desktop would break. Broken user profiles were a real pain. Thankfully I don't do this anymore but the thought of roaming profiles and broken syncs brought back a harrowing memory.