The main reason that expired domains are used, is due to the fact that the expired domain may have a good link footprint, that would save you a ton of time in building those. Without that good link footprint, then there's no difference in using a brand new domain, than the expired one, as both would be the same.
So when scanning through the expired domain, there should be some good indicator that the domain is a good one. For instance, having a high TF>30 would mean that there may be a high PR site that could be linking back to the expired domain. Scan through the domain's link profile, and if there are good links linking to that domain, then you will save money and effort in getting those links, and that domain would be worthwhile to be used as your money site.
I'd personally go for domains that are PA/DA>35, and TF>25, those would be good indicators of a clean domain.