Reply #80: Not really, what you may have heard is that Planet X may have life becasue there is water in it.

[liberation]

Or that Planet Y may be candidate to host life in it because it is within the so-called "habitable zone" (a distance from a start in which the surface of the planet is neither too cold nor too hot, just like our planet). Mostly because we only know life on earth, and thus that is what our knowledge is limited (you can't search for things that you don't know, or that your models do not predict, or you can not observe). Mostly because trying to prove a negative is generally not a good idea...