It's (to me) more plausible that they are just incompetent
They are very competent crooks. BFL was a scam from the very start.
Depends what you consider a scam. I think BFL did a poor job delivering these products but it's not a scam. They did make advertise their product to perform under the most optimistic situation they didn't put a warning saying that performance and ROI would change by the time the products flood the market.