For Crispy Chicken Thighs, Maybe Skimp On The Oil
Sometimes best practices in cooking can be counterintuitive, for example, in the case of oil. It seems as if using oil on the surface of a food would help to make it extra-crispy and in many cases, this is, in fact, true. Take deep-frying, which may possibly be one of the cooking methods most guaranteed to provide maximum crunch short of incinerating your food until it takes on the texture as well as the flavor of a charcoal briquette. There are times, however, when too much oil can actually detract from crispiness.
With chicken thighs, it seems that only a little oil is needed as the skin (which, of course, is a necessary component of crispiness) can act as somewhat of a sponge. While this means it can take on the delicious flavors of a marinade, it really does not need to absorb too much extra oil since chicken thighs are already fattier than breasts. Even without the skin, thigh meat typically contains triple the amount of fat found in breast meat. If you do want to rub your chicken thighs with a little olive oil before cooking, just half a teaspoon is all you really need and even then, if you skip it, the thighs will be nearly as crispy when they're baked.
You can also cook chicken thighs without any added oil
There are a few ways to get super-crispy chicken thighs that involve no oil whatsoever. One method involves dry-brining the chicken and leaving the salt on for a full day and night to draw the moisture out of the skin so it cooks up to an almost shatter-in-your-mouth level of crispness. While salt alone can make your chicken skin crispy, you could also add some sugar and other seasonings for extra flavor. As it just so happens, we do have a recipe for a tasty chicken dry rub.
Yet another way to cook chicken thighs without the need for any oil is to make use of their own fat as a cooking medium. Season the thighs as you please, then put them into a cold, un-oiled frying pan with the skin side facing down and cook them over a medium-high burner for anywhere from 10 to 20 minutes. (The lower end of the time range applies if you're using a nonstick pan, but a stainless steel one will take more time.) Carefully detach the chicken skin from the pan as it will tend to stick, then flip the thighs over and cook them for another 5 minutes or so or until a meat thermometer reads 165 F.