This has got to be 'Dick Spanner, P.I.'. He was actually a robot duck detective in a trench coat, which might look red depending on the episode. Super dark and noir animation style. Check that out, it's probably what you're looking for!

Definitely remember a show with a similar premise, though I'm not sure about the title you're suggesting. Back then, there was a trend of supernatural and occult themes in cartoons: think 'Gargoyles' or 'Mighty Max'. There were a couple of pilots that didn’t make it to full series, and they …