The worse problem is that even if you do research on the developers and owners of an app before allowing a permission that warrants a lot of trust, they can at

The worse problem is that even if you do research on the developers and owners of an app before allowing a permission that warrants a lot of trust, they can at any time be sold to a scummy company or data-mining agency who exploits the trusting user-base. This is exactly what happened to SourceForge.