I've fermented several ciders using glad wrap with no issues.
The last one I did though, I left for a while at ambient once FG was reached (autumn/winter melbourne ambient) and got a skin infection - not as atrocious looking as the one pictured but obvious and distinct.
I have had a similar looking infection/skin on beer left in the same way. Most of my beverages are in cubes with the lid tightened once FG is reached but I ocassionally use glad wrap for bigger batches.
Anyway, I bottled the cider with basically no headspace in each bottle (a precaution). Have drunk it all and given some away and had good feeback on all bottles but I would say when active ferment has wound down, all beverages of my experience may need to be transferred to airtight cube or at least watched for a bit.
No flavour contribution from the skin after 3 months but definitely something to watch out for.
I think greg is right in that glad, or headspace or even possibly airlock and lid with headspace are all good during active but reducing possible oxygen intake is preferable afterwards. Exactly how much oxygen ingress will occurr is anyone's guess and most beverages may not show signs of anything within normal drinking time.
It's just one of those risks you need to add in to which ones you are willing to take.
The above is based mostly on my experience and some theorising about said experience so please understand I am not examining my cider with High performance liquid chromatography, Gas chromatography, spectroscopy or analcolonoscopy.