Someone Else's Tree is not a source.

For your tree to have any real value, the information it contains must be accurate. Many gathering their tree information want so desperately to extend the line or make a connection that they jump to conclusions in their research picking any match to fill the space.  Some even make up connections to royal lines just to make a family line seem more prestigious and interesting.

Using Sources and verifying your data not only authenticates your tree but gives you an accurate archive of evidence about your ancestors, solidifies your family stories, and establishes your real place in history. 

This is your actual family. This is your heritage. Don't dilute it with the wrong information. Embrace who you are and your ancestors for who they are. You can draw real strength from learning about the events in their life. Were they farmers? Did they lose a spouse at an early age? Did they live during a war time period? All of these things can give you clues to the character of your ancestor. 

All of that said, My point is your tree needs to be ACCURATE. A mistake I see happening, all the time, is using someone else tree as a source. I hate to be the bearer of bad news but not everyone verifies their information. If you click on a hint in Ancestry.com, My heritage, or even Family Search you could be adding the wrong information to your tree. It can take months or even years to find the place the error originally occurred. Not to mention if you are a member of The Church of Jesus Christ of Latter Day Saints, this could result in doing the temple work for a person who does not belong to your family and sealing them to the wrong parents. 

In addition, by not verifying the sources YOURSELF you will lose out on precious discoveries. These discoveries come from carefully researching, digging deep, and pulling together details and uncovering new information about your family. 

The researcher from the tree you are looking at may have the marriage date and location of grandpa and grandma Smith correct, but because you never took the time to look at the marriage record yourself you will never know that grandma’s dad was listed as an iron worker or that she had a sister named Molly who acted as her witness, or that great grandpa’s first name is listed as Francis not Frank. This is what really makes family history research exciting! Don't lose out on that.