They have absolutely no resale value.
I've registered about 600 names since 2000 (500 of them in 2000). I've never registered a name with a hyphen it. I've only ever registered .net and .org to get a "set" (.com, .net. .org for the same name).
Main reason for not registering a hyphen is the problem saying the name to someone...passing it on by word of mouth. It's very very easy to get a half-decent .com . I registered one today for a WHOIS Lookup Service (in my sig)...whoislookupservice.com . It's a .com, doesn't have hyphens, describes the site perfectly, took me ten minutes and ten bucks to get it.
A name with hyphens would be ok for mail servers or the like, where no-one will see the name or needs to see it except the server admins, and it would be a bit easier for them to read.
I would say Condos-for-sale.com is the better of the two, because it's .com . You never know, you could persuade some real estate agent out there with more money than sense to buy it!
*the exceptional businesses of our esteemed moderators