This practice was so prevalent that almost any compiled genealogy is suspect. Even if the compiled genealogy pertaining to your ancestors was not fraudulent and came from a different time period, the author may have inadvertently included information from a fraudulently compiled earlier source.
Compiling a fraudulent genealogy was often motivated by an expectation that the recipient would be connected to a claim against an estate in England or the rest of Europe. The bogus genealogists preyed upon the gullibility and greed of their clients, giving them what they expected rather than accurate, correctly documented pedigrees. If you think this was just a passing problem of years gone by, you are misinformed. There are still unprincipled genealogists today who will provide a connection to royalty or a Coat of Arms for a price.
One of the problems we frequently encounter in Arizona is people who are trying to "prove" their relationship to an Indian ancestor. The motivation for this proof is a supposed and wished for connection to a reservation so as to get reservation economic benefits. In some cases, because of the huge incomes of the reservations, people are motivated to try to "get a piece of the action" by proving their Indian heritage. Of course, not all such claims are false, but it is interesting to see the number of people over the past few years we have helped who are so motivated.
The mere existence of this problem should be reason enough to examine any such claims, to royalty or Indian ancestry, with suspicion. It is important to carefully document any claim in a compiled genealogy before accepting it merely because it is written in a book. However, as noted by the Research Wiki article, "Armchair historians, family-tree climbers, and professionals are all among the guilty. Many are well-meaning folk who "just got carried away" by imagination, enthusiasm, or inexperience."
Here are some links that will help with avoiding genealogical fraud and scams:
- How to Identify & Avoid Genealogy Scams by Kimberly Powell
- Beware of Fraudulent Genealogies
- The Use and Abuses of Online Genealogy by Gary B. Hoffman
- Gustav Anjou, Fraudulent Genealogist
- Scam genealogical book
- Genealogy scams in general