I only use settings that I plagiar... design by myself and with the help of my friends. There's no canon to adhere to. Maps are usually hard to come by, as are detailed histories. However, anecdotes usually abound.
All I want to do with a setting is entertain. When players are interested in contributing, I'll incorporate their input. What I try to give isn't so much a base, it's more like tone, a few motifs, maybe a handful of secondhand recurring themes.
Which isn't to say I skimp on setting details. I invent scads. Some of them are even relevant to the action. And that's a special source of pleasure for me as DM; when I correctly guess which details will end up entertaining my players. When I succeed at separating the wheat from the setting-porn.
I try not to lose sight of the overall objective; providing a night of fun for my friends. Setting fidelity is only a means to that end.