I've seen people put Amiga stickers on all manner of machines.
Even an AS/400 machine, but that was almost appropriate: it ran Amithlon.
I've got Amiga stickers on one of those highly desirable super tall 8-bay AT cases. At one point, I had 18 hard drives, two CD-Rs, a Zip drive, and an 8-track player in it. Everything was connected to an A3000, and there was no other electronics in that case.
I'm with The OP here. Those apple stickers are obnoxious and have no place on those pieces of IBM history!! I am indeed PROVOKED by this! I guess I'll get over it. But it might take a while. I might have to travel to Madrid and remove those stickers myself. Good thing the seller doesn't want to ship to the US!
When i bought my first Apple iPad there was a free laser engraved legend you could add on the backside. It was free and was engraved at the manufacturer site. I think this option is still available if you buy directly from Apple Store.
I ordered the legend "intel inside". So belive it or not, my ipad has an intel inside, which would explain why it gets so hot.
Thinking about it I was actually wondering if it's possible the PC in question here had something like a Quadlink or Trackstar 128 Apple II compatibility card installed, which would sort of justify the stickers. But the shot of the back panel doesn't support that idea. (Appears to just have a modem, Multi-I/O card, and some sort of video card *not* an original IBM CGA or MDA. Given it comes with an MDA monitor it's probably something like an ATI Small Wonder.) Certainly possible it had one at some point that was ripped out later, though.