How to install freeware cleanly - a catalog of the most dubious crapware installation methods

The internet has brought about an explosion of free software that seems to just keep going strong. A lot of people wonder why so many people create and put out high quality software out there for free, and I am convinced that most of it is because people will put more of their heart and soul into something that they’re doing for free, that they wouldn’t if they were doing it for money.