"debt" is way too broad,,'debt' would include the payments on a $20k sound system/tv and debt on a house that is actually putting money in your pocket.
Is a mortgage on a cash flowing property 'bad debt', not in my book,,is debt because you went out and blew a lot of money on 'toys' bad debt, I would say yes.
Now, you can't say all credit card debt is bad, if you've ever purchased a house needing rehab with a hard money loan, you may charge things that you will be reimbursed for when you get the escrow money put up for repairs.
I agree with someone earlier, you have to remember who your talking about, Dave Ramsey is really more geared for a 'regular' employed person with no cash flowing business,,,,not someone that is a professional real estate investor that knows how to make money with debt.
If I followed Ramsey's model I would own 1 house, all cash,,and cash flow about $800 a month,,,I own 5 properties with debt and cash flow about $2750 a month,,,which do you think is better (and have over 25% equity in each of them)