Hasbro's pre-release publicity shots always make transformers look so sturdy and glossy/satiny. Mine do not look that good. Do they oil them up like bodybuilders, or what?
Various reasons! For a little over a decade, from Energon to halfway through Combiner Wars, they would use airbrushed/photoshopped/touched-up images of the toys, to give them a shinier look, though untouched photos made using production samples of the figures also existed and would often be used online. One my favourite examples of the “dishonesty” of this is this Universe redeco of Vector Prime - airbrushed on the left, untouched official pic on the right:
Today, the images used toys’ packaging, which are usually the earliest official promo images released online, are actually CG renders of the toys, rather than photographs of the finished product. But again, official stock images do exist that get used online. Compare Titans Return Galvatron:
Another common occurrence in publicity shots in the past, which is something that today we tend to only see when toys are in-person at Toy Fair, for example, is that the figure could be a painted prototype, rather that one cast in coloured plastic. As such, the all-over coat of paint can make the figure look much more glossy than it will be in its finished state.