How to tell if some information is right or wrong

I basically have found errors of one type or other on most documents.  So since scripture says the truth is established by 2 or 3 witnesses, After I find a tree with the information, I try to find a census, Bible info, Birth record, marriage record, land purchase, military record, etc to back up the tree.  If I don't find one or 2 of those, I don't post it in my tree on line.  I have a miscellaneous McCrory tree that I keep on my computer and when I connect it to something that I already have, I post it on my website, ancestry and rootsweb.  I also let everyone in my mccrory researchers' address book know.

I expect the dates on the documents to line up with reality.  IE: Girls got married and had babies at age 12 & 13 back then; girls did not have babies when they were under the age of 12; men usually got married between the age of 18-30;  occasionally boys got married as young as 16;  it was not unusual for Mom or Dad to live with a child when they got old; during the civil war and American revolution kids as young as 12 and men as old as 70 fought in the war out of necessity or because they were healthy enough (Caleb was 80 when he fought for the promised land); never say it could not happen or something out of my paradigm should be impossible because it could. 
Just because I can't find something does not mean it's not true or that the person does not exist.  They just may not belong in our tree.  After I decided they did not belong, I found 5 or more years later that they did because I did not see that infant on the census page with their parents - he was at the top of the next census page.
I discovered that a military record can tell you more about a person than a census.  It gives their birthday, color of skin, height, build, color of hair & eyes, disabilities after the war, if they are married and how many children they have at the time.  It also shows if they can read and write or not.  Up until the Korean war, even though you signed up for the draft, they did not make you go if you were the sole provider of your family. 
That's just a few things I have learned sense 1956.  The greatest asset to a tree is living relatives and fellow researchers who keep in touch with each other.  Love my research buddies.