Here's a quick poll of my older collection:
Records in PVC sleeve:From 56 examples:
Both Sides Affected: 21 (37.5%)
One Side Affected: 8 (14.3%)
Neither Side affected: 27 (48.2%)
Records Not in any sleeve:From 28 examples:
Both Sides Affected: 1 (3.6%)
One Side Affected: 5 (17.8%)
Neither Side affected: 22 (78.6%)
And here's an interesting exhibit:


The effect that I'm trying to show is not easy to photograph but it should be discernible that the bubbling of this record sleeve has a different pattern at the label area of the record. I have a couple of others wherein the label area is flat, surrounded by the bubbling. I should point out that a minority of sleeves in the collection show this type of effect to any degree. Oddly enough the record inside is one of the unaffected ones but another Oldfield disc close by was badly affected on one side only. It's entirely possible, I suppose, that this sleeve has been affected by an adjacent record. This evidence proves, though, that there is some interaction possible and in fact happening between the vinyl of the records and the plastic sleeves.