"Unlike shopping for a bank or a refrigerator, in the case of online dating, the refrigerator has to like you back," Gilman said.

"There is a different level of exposure to disappointment and that's captured in the poor overall scores." Once considered taboo, online dating is now a socially accepted and booming multibillion dollar business that continues to grow.

(A score of 100 indicates respondents were completely satisfied; 80 was very satisfied and 60 was fairly well-satisfied.) Still, many users found the sites frustrating.

number of online dating sites-18number of online dating sites-90number of online dating sites-54

A 2005 study of data collected by the Pew Internet & American Life Project found that individuals are more likely to use an online dating service if they use the Internet for a greater number of tasks, and less likely to use such a service if they are trusting of others.

It is possible that the mode of online dating resonates with some participants' conceptual orientation towards the process of finding a romantic partner.

Still others rely solely on paid membership subscriptions.

Opinions and usage of online dating services also differ widely.

More than half, or 53 percent, of single people have created a dating profile, according to Match's recent Singles in America study, which polled over 5,000 single men and women in December.

Today, 40 percent of singles have dated someone they met online, while only 25 percent met a first date through a friend.

Other sites target highly specific demographics based on features like shared interests, location, religion, or relationship type.

Online dating services also differ widely in their revenue streams.

Most services also encourage members to add photos or videos to their profile.