I can only assume from your very brief post that you figure that since we are exploring Mars, NASA scientists think there is or was life there.
It is not like that at all. In fact almost the opposite is true. NASA scientist, being scientists, are obligated to think critically and scientifically. They are explorers. They are exploring. They are trying to learn. And as history has shown, we often do not know what we do not know. We have no idea what we will find or learn.
I'm so happy to learn that we have such a noble and honest knight to come to the defense of our and their scientific purity. So, I guess, they are guilty of lying then, if they're advocating something they don't really think there is a possibility of seeing any signs of. I've pointed out to you the locations on their website where they mention a quest for life. I would think that might just be political BS put on by their PR department (on your word) if it were not the real names of NASA scientists at the bottom of the pages labeled as content managers.
As much as you may desire that they don't go looking for something that has a fairly good possibility of being true, in the name of some sort of queen-sized idea of scientific purity, then you need to take off the blinders. There is nothing wrong with, no skeptical attitude that demands, that a scientist might think that life may be present on Mars; life is one of those physical facts, the determination of which will enlighten the study of biology whether they find it or not. They will, of course, draw conclusions as the evidence warrants. How in the world do you think they can plan missions and create experiments if they believe that they must inevitably be failures?
And being scientists, they are sceptical and they do not subject themselves to believing something on hopes and dreams like undergrad sci-fi fans who tout "I am sure there is life on Mars"
And you are equivalently sure there isn't, and NASA had better agree with you, eh? Otherwise they're not being skeptical? They're being undergrad sci-fi fans? You sir, need to deflate the ego just a mite. Ye gods, you make it sound like some sort of viral infection.
I have spoken face to face with NASA scientsts. I was lucky when the AAAS had a meeting down the street from where I worked once and I had lengthy discussions with several NASA scientists. They expressed excitement about exporing Mars because we will have no idea what we might find. None expressed excitement about finding possible life there. And they all doubted it.
There was a time, after the negative results from Viking in 1976 seemed to kill the idea that there was life on Mars, that there was a lot of gloom (no other word for it) on the subject. I wouldn't be surprised to find that your experience came from that time. At that time we had no data on Mars' natural history. Today, thanks to the plethora of explorative robots on and around Mars, that negative outlook has been miigated by the fair chance that life at one time did exist on Mars, and that remnants of it may still exist. No certainties, for sure, but scienists don't have to proceed from an assumption of total lifelessness as you imagine.
Get a grip. No one expects to find Barsoom in a cavern under the North Martian Pole, sucking on that ice cube buried there. But they may find some microbes, and if they do, than that will extend biology's whole realm by a factor of two overnight. That thought does excite scientists, biologists and cosmologists in particular; even Spock (
http://www.griffithobs.org/pnimoy.html) is looking forward to the discovery.
I know this is unlike what we would like to believe. But it is the truth.
Some skeptical attitude, fella.