How to spot a low quality Web Directory:

1. Domain name – A suitable domain for a directory generally should contain words like: directory, dir, submit, link, url. Or it may be a brand like: jayde, busybits, abilogic, etc. An unrelated name like: estimamo.com, jhucr.org, mw06sv.com is a strong sign of a dropped domain. The best way to check is archive.org. Some people buy dropped domains with page rank and quickly setup directories, then start to sell links. Eventually Google penalize the sites and then they become inactive or closed. Never waste your money or time with dropped domains!
2. Design and customization – Long term established directories use custom designed templates. Short term, low quality directories use free templates. Also look for a contact page, contact from, submission terms. A quality directory will always provide you with help pages and contact info.
3. Home page and sitewide links – Serious directories like: DMOZ, Busybits, My Green Corner, will not have links to other sites from their homepage and they will not have sitewide external links.
4. Empty categories – Go to /Arts or /Science categories and check if there are sites submitted. Poor quality directories often have empty categories.
5. Directory age – Try to choose directories that are at least two years old. Use whois on the domain and archive.org to check this.