Is MacKeeper usually a scam?

MacKeeper is a legitimate software program, according to Leander Kahney of Cult of Mac. Kahney cites several positive reviews of the software from legitimate sources such as Macworld Magazine, TUAW and Backbeat Media, along with its existence in the Mac App Store as proof that MacKeeper is a legitimate program.

MacKeeper's bad reputation among Mac users is likely due to negative PR from rival software makers and aggressive marketing tactics by Zeobit, developers of MacKeeper, according to MacKeeper’s PR Director Jeremiah Fowler. Another issue is MacKeeper's name, which is similar to Mac Defender, which was discovered in 2011 and described as the first major malware threat on the Macintosh platform.