Like their script kiddie counterparts, op kiddies are typically young and male, with little grasp of spelling, grammar, common sense or server management. Their sites are normally quite barren activity-wise for several reasons:
a) They don't manage them well enough to attract many (if any) regular members.
b) They are often hacked due to the op kiddie's failure to keep up to date with applicable software patches, or just general naivety when it comes to security. Successful hack attempts can result in total data loss, which isn't likely to make any pre-existing members want to stick around. Of course, the op kiddie won't have made backups at any stage, either, so unlike competent webmasters, they are usually unable to simply restore things to how they were.
c) The idea or theme behind the site is unoriginal or poorly thought out. Quite often, the op kiddie will simply create a "general discussion" forum which in fact has no main theme at all, then advertise it somewhere in a manner along the lines of "comme 2 my genral fourm takl abuot aynthign!!111". Naturally, they will be unaware of the existence of, say, offtopic.com.
d) The op kiddie keeps breaking things on the site and disrupting service to the users, which is a sure-fire way to make people vote with their feet.
The existence of op kiddies is not only irritating and amusing (sometimes, at least), but also dangerous. Most internet users think nothing of submitting personal information to websites at the drop of a hat because they quite understandably make the assumption that the person in charge knows what they're doing. They may however have second thoughts regarding this when they visit the site later on only to discover that it is now a blank page, or there is a cryptic message from a Turkish hacker group in its place, or sensitive database information has been leaked thanks to a security hole and their email is now known to spammers.