If you're talking about the home page having PR 0, check the site command in Google to see if their pages are indexed (site:domain.com). Look for spammy ads above the content, and look to see if they are linking to bad neighborhoods. Also check the whois of the site to see if they are not a new site. If they are an older spammy site promoting bad content then I would ignore them as they might have been penalized. However, if they look like they have quality content, and are a new site then I would go ahead and submit because their PR might rise in the future at which time they will likely start charging for reviews.
If you're talking about PR on the link page it is rare to see any directory these days with PR on the link pages due to Google removing PR from all directories a few years ago. Those directories that have PR on their link pages usually have No-follow on each link.
Yes,there is no use of submit your URL to zero PR directory.This will be wastage of time if you do so.While Submiiting your url to high PR directory firstly you have to choose a relevant category after that you can submit your Url to that one..:)