...not even warm ones. Every temperature anomaly that has been investigated has proved to be due to rocks warming in the sunlight and cooling at night. Don't think that there hasn't been a LOT of effort on this one. There have been good IR detectors in orbit for at least 5 years, and still nothing.

The obvious volcanoes have been checked - zilch
The source areas of outburst floods - zilch
the edges of the polecaps - zilch
big craters - zilch
small craters - zilch
sulphate areas - zilch
White Rock - zilch
Random areas - zilch
Data mining - zilch
anomaly detection - zilch

If you have any good ideas that a whole cohort of graduate students and their supervisors have missed, I'd love to hear you articulate it clearly, but vague arm-waving is not good enough.