I also use it on location all the time so it's subject to dust.
What should I do?
For your needs I would think you need to consider switching to getting a Sager 17" 1080 HD anti-glare with Windows 7 instead.
Not only are 3D gamers computers more graphics and CPU powerful, up to 32GB of RAM as well, but they can be opened by the user to clean the dust out of the cooling fins.
They also allow for multiple internal drives etc. for more of a portable workstation purposes.
Apple has been steadily decreasing hardware performance in their portable line, only provides one top end 15" model with more powerful dedicated graphics when last models all 15" had that option.
Also Apple has sealed the newer machines up, so one can't open them and remove the fans to clean the cooling fins.
If the cooling fins are not cleaned often in dusty environments, it greatly shortens the working life of the machine.
Severe dusty environments can be considered a "user inflicted damage" by Apple which isn't covered by AppleCare or warranty, much like liquid spills are also not covered.
My previous 15" was used on many locations in the field, after only a year, when I started experiencing problems and Apple couldn't fix, I took upon myself to open the machine and see the cause of the problem myself.
The coolin fins were half choked up with debris, hindering the exhaust and slowly cooking the video graphics as it's the hottest part of the machine.
Clearing the debris didn't work, the heat damage already occured.
Mac's are designed for lite clean office like uses only, nearly all, except the MacPro, are not designed for heavy duty use and adequate heat removal.
Thanks for the feedback, problem is that Macs are industry standard in my line of work. Also not to sound fany boyish but it's critical that the machine functions at full capacity all the time, without any problems and PC's and especially Windows is prone to crashes.
As yet, I've never had my mac go down on me and it works super hard for hours at a time.
I do think it's odd that the dust actally managed to melt into the screen.
I have the same issue.
I have got 2 melted cavities on display of my mac book pro retina 15".
I investigated it and I am pretty sure that it is not melted dust.
What I did:
1. cleared screen very carefully by rag with apple sign (that one which is being sold with macbook pro retina).
2. connected my mac to external display
3. closed notebook
4. run task which loaded CPU for about 50-60%.
5. in few minutes I opened notebook and touched display at top part. it was cold and only bottom part was warm.
not hot but just warm.
6. when I carefully discavered display I found new dot at TOP part of display.
Conclusion: coverage of display is not glass but some kind of plastic which don't like even warm air.
It was not heated to be even warm but small area of display is melted.
So in order to save you display NEVER close it till it is powered off or you will break you display surface.
Also I think you thould wait for a few minutes even you powered off you mac to prevent gathering hot air under lid of notebook.