It is most likely an issue with the orientation tag within the JPEG metadata.
Since VGCollect cannot be turned sideways, it has no use for orientation tag. So yes, the reason why the picture appears OK for people viewing it is because the program they are using is not showing them how the image actually is, but is reading a part of the file and changing its appearance based on that.
Anyone who finds an entry with a sideways picture, please try to replace the image with an edit. If you can't find a picture to replace it with, report the item in the Listing Errors thread.