One of the reasons that I've been glad that I've posted my lines to places like Rootsweb's WorldConnect is the number of corrections and additions to data I've received. I've been fortunate to meet many new cousins and to have others correct errors that have creeped into my database over the years.
When I first started putting my genealogy into the computer and was able to go online, there were many names that were added whose connections have later turned out to be erroneous. In essence, I was a 'name collector', eager to expand my data and certain lines back too far too quickly. It has been and continues to be a tedious process to weed out errors and properly source data. Even though my data may have some errors, I would rather post what I do have online in the hopes that someone would correct me than to leave it incorrectly in my database for someone to find later.
Recently, I received an email regarding the COLLINS line that I had posted earlier. The gentleman questioned my parentage for Jonathan Collins, and he pointed out that it appeared that the line that I was showing in my database was a corruption of another Collins family line. As I didn't have any source data for these additional two generations past Jonathan, I have come to the conclusion that he was correct and have deleted them from my database. One error down, unknown many more to go.
At WorldConnect, I freely admit that my database is a 'work in progress' and that I welcome corrections to the data. Those branches that have been sourced I will stand behind, but will also willingly seek corrections and additions.