It is important to know that for any project hoping to convince investors into putting their money into the project, they are going to be focused on making the project as appealing as possible which means that the project's whitepaper will surely be good so I believe you should look beyond the projects whitepaper to decide if a project is legit or not.
Always make through research of a project's team, road map and token metrics to decide which projects to invest in
The Whitepaper is the first to learn a potential investor, so its main task is to interest a person. Of course, you can not completely trust this, but an experienced investor can see whether this project is good, with the help of a whitepaper.