Do you ever read compiled genealogies? Your answer is probably “yes” and if it isn’t, it probably should be. Part of doing research is understanding what has already been done.
Once you know what has been done the next step is to figure out if it has been done right. The next step is not to believe everything you read.
Some compiled genealogies will be accurate, honest about what is not clear, explain conclusions and cite their sources. Many will not. They will be questionable, state hypotheses as if they had been proven, make statements that might be correct but that are less than obvious and not supported by evidence or logic.
Compiled genealogies are not reality but they are at least attempts to map reality. Like following a real road map, you can use the map to help you find your way but you still need to look out the windows and rely on reality as you drive.
Even with all the caveats about compiled genealogies, they often are very useful. Sometimes they will contain facsimiles of records, other times they will cite their sources and make it easier for you to find them and confirm them.
Hints
Sometimes the genealogy will not tell you the origin of the information. If it is information worth understanding, that is when the fun begins. Sometimes the information itself gives you hints about the source.
Daughters who seem to have all married men with surnames but without given names? That smells like the father’s probate records have been found. Either his will or a list of heirs may give all the married daughters by their full married names. If you didn’t know that there were probate records, that is a handy clue to have. If you had looked but not found them, there is nothing to aid persistence like a fresh reason to believe that it will pay off.
Is a name consistently spelled differently from the way you have found it? It may mean that the author relied on only a source or two for the information about that person and the source that gave them the spelling is one that you have not yet seen. These small discrepancies can be clues.
Is it clear that the author has confused two people? Time to ask yourself what that means about the documents that the author couldn’t have seen. He couldn’t have seen John Doe’s will that names his nephew, John Doe. She couldn’t have found the census that has John Q. Public a few lines away from his cousin John K. Public. Then ask yourself what more subtle problems will appear in the author’s work without that document—things in their writing that might lead you astray otherwise. You can also ask yourself how the author knew a few things that you know only from the source that the author never saw. Is there an indication of a source that you haven’t seen?
Does the author have very different things to say about a family than what you have? Someone is wrong. Be open minded about who that is. If you have a good deal of documentation to back you up and the author doesn’t cite a single source, be wary but perhaps it would be a good idea to try to understand where the author went astray. You just might learn something. Remember too that just because you figure out why the author is wrong, it doesn’t prove that you are 100% right.
This sort of metagenealogy can be a fun mental exercise in its own right but it isn’t the same as actually getting your hands on the documents themselves and understanding what they have to tell you. It can be fun to stare at a map and plan a vacation route but that isn’t the end point. As fun as map staring can be, you still need to hop in the car and go see the sites for yourself.