Like the old adage says, "Buyer beware."
Even if you aren't actually spending money to obtain family history information, it's still prudent to pay close attention to what you find.
Someone related to me somehow has identified this photo of a woman standing next to a man who is seated. Yes, they are probably husband and wife. But are they the right husband and wife?
The unknown cousin has posted this photo on Find A Grave and has identified them as John Frederick "Fritz" Reed and his wife, Mary Eve Groves Reed.
Whenever I see it, I get really annoyed because I am certain they are misidentified.
First, both were born in the 1760s. Photography wasn't a commercial industry until 1839 – 1840 in the United States. Judging by the clothing this couple is wearing, this photo was probably taken in the late 1840s or 1850s. They appear to be in their 40s, perhaps.
The couple is far too young to be Fritz and Mary Eve, who would be in their 80s or approaching 90 at the time this photograph was taken.
What's more: Fritz died in 1836. Therefore it is impossible for this photo to be of him, even if he had aged extraordinarily well.
Fritz and Mary Eve had a son, Daniel, in 1796. He married Mary Tipton in 1829.
If the photo has the name Mary Reed written on the back, then the person who posted the photo originally made a huge assumption. The most basic problem with this assumption is that having a photographic portrait made wasn't even a "thing" yet when Fritz died.
If indeed the name Mary Reed is on the back of the photo, it is more likely to be a photo of Daniel and his wife, Mary. Daniel died in 1849, so if my hunch is correct, it must have been taken not long before his death. It could be a post-mortem photo of Daniel, but I would need to see a better copy or the original to make that determination.
So, always remember this most basic caveat when doing genealogy research: Never take anything as fact until you have the documentation to back it up. Analyze any information you find in someone else's family tree or posted elsewhere online before accepting it as fact and adding it to your own tree. Or Find A Grave.