Nimbostratus
NimbostratusSSL shouldn't cause a formatting change (I'm assuming you mean of the rendered web page). SSL happens at layer 4, the HTTP calls are at layer 7.
That sounds, to me, more like either a persistence issue where on the ssl enabled vip you are hitting different backends and one of those backends has slightly different version of the page (which there can be many causes for, caching can be one, but there are others) or you are unable to retrieve one or more of the objects from the server when going over SSL (say a style sheet or an image) occasionally thus affecting the browser rending of the page. This might not necessarily be happening at the F5 itself, as well, if you are going through a transparent proxy for example (BlueCoat or the like). I've seen those cause issues with some renderings as well.
It would be helpful to see the config of the virtuals and pools (sanitized for your protection).