I've never eaten a Dorito but the internet confirms they're some kind of synthetic tortilla chip substitute. I mean, why just roast a tortilla to crispness, when you can combine 1,000 ingredients in a machine and make something that looks like radioactive cardboard triangles that has none of the health benefits of radioactive cardboard triangles.
Ranch dressing is traditionally buttermilk, sour cream, mayonnaise, garlic, and dill, and is quite nice. Whatever you buy in a bottle from a supermarket, on the other, hand, who knows. I don't think I've seen it in the UK, but it's ubiquitous in the US as the most popular condiment. Weirdly, although I don't like blue cheese as it is foetid, I do like bleu cheese dressing, it's truly the only thing to go with buffalo wings. I don't know what makes blue bleu, but it's successful.
The worst snack I've ever eaten is baked pita chips. They truly are like eating extra dry cardboard and woodchips.