Ugh, that's interesting: it looks like that Photoshop CS5 is somehow adding those spaces in the description field. It doesn't happen if I resize the photo with another software.
It didn't happen with my previous Nikon D80 camera nor it happens with a Samsung S4 Mini.
It seems that the issue occurs when editing JPG files produced by a relatively recent Sony A6000 camera.
What's even stranger is that Windows 7 x64 doesn't show such empty spaces in "file properties --> desciprition".
It doesn't happen if I upload an untouched 24Mpix A6000 JPG file, so it's definitely Photoshop CS5's fault.
I may disable IPTC data import feature, given that I don't insert location/title/keywords in the JPG file.
Otherwise, if you want I can attach an A6000 jpg file, and if it turns out that it happens with more recent versions of Photoshop, an exception for A6000 desciprion field could be added to cpg source code.