The paper shows an interesting geographical clustering that I would like to investigate further.

However, it is typical of the "Water on Mars" school that if something looks like water on Earth, it MUST be water on Mars.

There is no analysis of what surface conditions on Mars would do to a water seepage. To me it seems obvious that dark water stains would not persist unchabged in shape but gradually fade over a period of years. Instead, I would expect the water to freeze within days, and sublime away in months.

The Authors keep mentioning that liquid water may be stable in some areas of mars, due to warm temperatures and moderate atmospheric pressures. However, they fail to correlate this with the areas where they observe "seeps". The reason they don't do this is that the areas they identify are typically too high altitude for water to be stable, so their entire argument is a bit of a waste of paper.

Those gripes aside, it's nice to see people trying out some ideas. I will look into some of these areas over the next (long) while and see if any ideas pop out.