Listed are various styles of some kind of deinonychosaur.
Almost all animals portrayed in this chart can happen for one reason or another naturally. Naked faced and naked head and necked dinosaurs occur now, and would've likely done so in the past as well. The Nopes are more of a 'this is not how ALL deinonychosaurs looked', which some people seem to actually think,for one reason or another. Variation happens and, even within the same genus, it's possible to have wildly different feathers or baldness(On the head and neck).
In the first row, the first listed is the template for the rest. It is completely naked. This is how the media (JP) portrays their raptors.
yes, the raptors in JP are naked, NOT scaly.
Here we have a list of peculiar stereotypical raptors, from those who may have used a skeleton as a reference, but didn't research integument(body covering).
The first one is a very very common occurance, it is known as 'shrink-wrapping' and is usually played off as 'i did my research' as far as the shape of the skull goes(this is often not the case however), OR is used to just give extra detail to the skin. The real animal wouldn't likely have the holes in the skull showing extensively, unless they were starved to death. Some people even make the holes in the skull show THROUGH the feathers, that's crazy!
The second is the JP3 or Talon(from Primal Rage) style, where the raptor has a few feathers stuck to the top of it's head, maybe a couple on the arms and tail too. This is the equivalent, in raptors, as having full blown and horrific mange.
The first two may also be drawn by people who 'don't believe' in feathered dinosaurs, often equating them with chickens.. despite there being many many cool and badass avian dinosaurs around today, like the harpy eagle!
The third image is what is commonly seen in what people call'half-bird' dinosaurs like archeopteryx. They don't see birds but as weird feathery lizards, and this style reflects that. Some dinosaurs may have actually had naked heads, for a variety of reasons, however, much like vultures or turkies do.
Fourth is about the same as the third
This row are styles commonly used by artists that know how to feather the dinosaurs in a plausible and reasonable way.
There's actually not much to say on them, and the possibilities are nearly endless, especially depending on style.
The major fluff and 'go crazy' row. These are all fairly plausible in some line of deinonychosaur and is seen in modern day avians
The first imagine is a raptor with owl-like feathers
The second is one with thin whisker-like feathers and eyebrow crests
the third is one whose feathers form a shape like that of a pigeon.
This row has seemingly infinite possibilities and is the most fun.
I don't know about others, but I've never liked medium-to-large deinonychosaurs depicted with feathering around their mouths or extensive head plummage. People who do this seem to not understand the main reason why most vulture species have bald heads - to eliminate hygiene issues associated with often having to stick their heads into carcasses while feeding. Feathers, while stronger than mammalian hair in most cases, do not take well to bacteria and tend to rot away if not cleaned properly.
Most people try to come up with explanations of larger deinonychosaurs hunting young animals or prey smaller than themselves (such as occurs with modern raptors and owls), but considering they lived in a world where they were literally surrounded by giants, I don't see much sense in this argument. Very few African predators will pass up a chance to scavenge a meal from a dead elephant, hippo, giraffe, or various other mega fauna. Why would such habits have been any different for Mesozoic predators?
The actual reason seems to be a thermoregulatory adaptation to cope with the extreme temperature change when going from hot low altitude air to cold high altitude air.
Another thing about New World vultures... the northern species migrate according to daily temperatures. As long as the high temps for the day are enough to allow carcasses to thaw out for consumption, they won't leave even if there's snowfall at night. If the lack of head feathering is about thermo-regulation, I would think they wouldn't be able to take the cold.
There's also the fact that the North American New World vultures don't have the additional bald patches that Old World vultures tend to have.
P.S. in response to your petrel comparison: Petrels are seabirds whereas vultures are not. Their feathers have additional adaptations against moisture that vultures and other non-waterbirds/waterfowl do not possess.
btw I'd like to see sources for several of the claims you make, like feathers rotting if left unclean or giant petrels having specialized moisture resistant feathers that guard them against constantly leaving their heads covered in blood and guts.
Larger deinonychosaurs most likely DID attack smaller prey,or weaker prey, however predators will generally do whatever they want. An animal would rarely pass up a nice and free meal.
The biodiversity of Ornitholestes deinonychosaurs dromaeosaurs and Troodontids surely didn't move in a straight line to birds and for those of us who are not materialist and do not uphold the world's most popular creation myth the idea of saying if more then one descendant has a trait than the ancestors must also is illogical. Have you found feather impressions for every species of Ornitholestes deinonychosaurs dromaeosaurs and Troodontids I think not and in time. You will find that People will look back at the age of bird dinosaurs just as they look back at the age of reptilien dinosaurs.
Dinosaurs are both unique and diverse!
^^' I've even made a few bald faced or naked throated ones myself, as seen there for a basic deinonychosaur, and here as well, so I'm not fully against them in terms of alternate interpretations and variation on species. I just made this to show that 'raptors' aren't scary feather covered half-lizard freaky monster things.