Well yes, you expect to see grass as being green so the brain tells you it is green by doing the colour conversion for you! I agree with you it does look green but isn't really if you look at it closely.

Doesn't if you prefocus with the rear button before taking the shot. Any camera is likely to hunt using the half-press on the shutter release at the point of exposure. If one keeps the camera on a permanent autofocus system it tends to eat the battery faster due to the fact it is always hunting for the perfect focus. Par for the course.
What would be the point of pre focussing an image accurately only to have the camera change it at the moment of exposure when the shutter release is pressed? (And it isn't just Pentax cameras that would do that if you let them.)

Stop buying more!

Perhaps they get a better price jumping in at the last moment in an organiser's 'fire sale.' (Trust not literally! Last time I went into B&M the store was a pile of ashes an hour later! Scary.)

It probably isn't the monitor but the brain being tricked.

Similar to this:
http://mentalfloss.com/article/71252/trick-your-brain-seeing-black-and-white-pho...

I find cameras without a viewfinder very hit and miss to see anything meaningful on the live view screen, and the brighter the sun the more the problem. If the camera hasn't got a viewfinder I normally point and hope for the best! Not really an ideal methodology.

Let us know how you get on once you have obtained it - fingers crossed, eh?
As to your current one, have you had it long? Any chance of returning it to the supplier to have it serviced, replaced or refunded given you've determined it's not fit for purpose?

Does it look in focus in the viewfinder?

.. and to add to that, sometimes one has to press the AF button several times before it focusses where one wants it to. People often blame focussing issues on the camera when the reality is the camera has no idea what the person taking the photo wants in focus and what they want out of focus. The camera just does its own thing if the photographer doesn't take charge!