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Depends on what you define as being "life". Remember, carbon can make an enormous range of organic molecules, many of which we most likely haven't even found yet. There could be organic molecules in living systems on other planets that are so robust that they can survive in conditions which might completely destroy our forms of organics. What about life on carbon rich planets. The medium for dissolving organics there would be petroleum, not water. What about life on those planets. Just because a planet looks harsh by our own standards doesn't mean it can't support life, or isn't supporting life presently. Even on planets like our own, just because the water has other compounds dissolved in it doesn't make it inhospitable. Looks at the black smokers along deep ocean ridges. The pressures and conditions there would kill us stone dead in an instant, yet life flourishes in these environments...and it's fundamentally the same as we are, physically and biochemically.
I think we have to be very careful about being a little bit too narrow minded about our definitions of habitability and life in general. We can miss out on seeing the life present in an environment where we deem it unsuitable, just because our scientific paradigm at the time says that to be the case.
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