All that you say is true, and relevant.

What I'm trying to do is to get people to start from a rational and defensible view of Mars' surface, rather than the nuts (yes, you know who you are) who claim there is pure fresh liquid water everywhere, clouds with rain, morning dew and all that Terrestrial crap.

Mars is F'ing cold. any H2O there is either frozen*, or so saturated with acids and salts that we would hardly call it "water".

That's the base case. To work on possible Martian biology you have to accept this - indeed embrace it - rather than deny it. I have my own crazy ideas too - in the Northern plains, for example, there are odd dark dusts that emerge from fissures <a href="http://www.msss.com/moc_gallery/e01_e06/images/E04/E0402277.html"(like here), or from under slowly shifting dunes. One extreme possibility is that these are particles of reduced carbon - evidence of a metabolism in the subsurface that sequesters oxygen from atmospheric CO2. In my rational moments, I don't think this can work, but it's the sort of idea we need to chase down to confirm or deny life on Mars. (These dark dusts seem to have the spectral signature of finely ground mafic minerals like pyroxenes and amphiboles, rather than amorphous carbon, so the evidence is actually against the crazy idea)

Dreaming about waterfalls and mud and rain won't ever get us insight into a cold dry planet. All our instincts are wrongly-tuned for Mars and we must be clinically rational in our analysis of surface and subsurface conditions rather than relying on "common sense".

* Caveats:-

* Monolayers can exist unfrozen down to -25 C and more. To a degree, salts additionally reduce freezing point.

* Geothermal (Areothermal?) hot spots could generate liquid water, but to date we have not found any despite an exhaustive search

* Subsurface water can be liquid of course, but it has to be really deep - Mars has a MUCH lower heat output than Earth and you need to be about 10 km down before pure water would melt

* There are plenty of areas on Mars that have transient surface temperatures above 0 C and pressures above the triple point of water so liquid water is THEORETICALLY possible there. Unfortunately, these areas are likely to be the deserts of Mars - drier than the average purely due to their regular heating. A much more careful analysis of transient temperatures in the presence of ground ice, and the interaction between atmospheric and surface moisture is required to make a good case for morning dew, or whatever...