Guytronic, what's certain is that new 535 have a new touchpanel. On a French forum, there's a dedicated 535 thread where people share their touchscreen frustration and report repairs, etc. (like here). Recently bought Lumia 535 (they're all dual sim in France) have their proximity/ambiant light sensors visible, like on my repaired 535 (see picture above :
http://forums.windowscentral.com/lumia-535/331929-9.htm#post3052654)
This means that progressively, the touchscreen issue will be a urban legend, Microsoft will state that it was a SW issue.
My new screen is :
a) less pale : vivid colors
b) less "greasy": my first touchpanel had a kind of white veil, if you see what I mean. My new screen reflects less light (noy comparable to mid or high range though)
c) and of course : registers 5 fingers without a problem.
Now that new 535 are manufactured correctly, in 6 months, nobody will mention that touchscreen issue.
And you're right. Non geek people have probably returned the device, or added a screen protection.