There is nothing wrong with butter, oil, or dressing in moderation. If it makes a rather boring dish more interesting, it's worth it - none of those things up the calorie count too much.
p.s. wtvanhest: Not sure what you have against blue cheese. Hopefully not "dietary fat makes you fat because it's calorie dense" because that would again be anomalous 80s thinking that ignores satiety effects and runs with a 1-dimensional model for something as complex as nutrition and aggregate consumption behaviour.
So long as you're aware of what you're eating it's fine.
If you can't understand why you're still 17 stone you might want to look at whether you're having a blue cheese dressing on a salad but counting that snack as 0 calories, which is something a surprising number of people do. They have their 3 meals, which come to something like 2,000 kCal per day, but they don't count all the other snacks they eat.
Satiety is important, but it's still calories in vs calories out.
Palm and coconut oil are much better than sunflower or corn oil, in part because of something called the smoke point.
And calorie count is not that important if you eat the right things.
What I do know is that the more refined an oil is (and therefore less rich in flavor and nutrients), the higher its smoke point will be. The implication being that you should pick virgin/cold-pressed/unrefined versions when you don't need the high smoke point for your cooking. Is that what you were getting at?