Reviews of MacKeeper are generally unfavorable with questions raised about the validity of some positive reviews. IMore notes that the software destabilizes what is a relatively stable operating system, OS X.
IMore also notes that uninstalling the program does not fully remove it, and that extra work and knowledge are needed to completely do so. The Safe Mac claims that the advertising of MacKeeper is unethical and intended to sneak onto the systems of unsuspecting users. This includes using fake websites speaking positively of MacKeeper in order to advertise and improve the company's reputation. Apple Insider notes that the company has been forced to pay out a settlement for a class action lawsuit and that the software can produce false positives.