I use CD-Rs but it's because my CD sales are a cottage industry. I'll press maybe a dozen if I've got a gig coming up. And I don't sell them. I give them away in return for a contribution to charity of around a fiver. And I use the cheapest I can find with stick-on labels. Do I ever encounter problems? Well, yes. But not very often. Not often enough to make me want to go for a more expensive product. Sometimes the CD won't play beyond a certain track. But they're usually okay. And I've never had any problems with the sticky labels. But they don;t go right to the edge (see John in Kansas' post above) and I use a gizmo to make sure they're centred correctly.
I'd feel funny about pretending they were pukka CDs worth £10 or more, though. I say "They're promo CDs".