i've used them only once. I agree they are a wierd service. they say two days to your bank account, then it takes a week. they do all this wierd shit to confirm your identity, which includes random ass questions about some address you lived 10 years ago, and about random people from your town. fucking wierd as shit. then, you always fail the identity verification, its so fucking dumb, and an obviously rigged system to prevent you from getting to level 2 or 3 or whatever the hell it is. So in the end, they aren't exactly a scam, they are just a strange bunch of folks with odd ball ways of doing things and a misleading company line.
Those questions probably come from credit bureaus that have a history of your addresses, etc. I'm assuming this means they check with them, however after they canceled my order I checked my credit report and it was completely clean. The algorithm they use to catch "high risk" transactions is opaque and does not appear to be very accurate, so it's obviously open to manipulation for Coinbase's profit as well. I don't know whether there is systematic or manual manipulation of the algorithm or flags in order to profit at the expense of their customers, but I can't rule it out either. The additional problem of unresponsive and unhelpful customer service just makes me stay away.