The only dogs allowed in the passenger compartment on airline flights have to fit in carriers that are small enough to fit under your seat. This means that they are very small dogs who do very small poops. And they give you living hell if you let them out of their crates during a flight... Not to mention that it costs around $100 extra to do it, so very few people do.
I am around 99% sure that it was not dog poo.
Not true at all. They have full grown german shepards on flights.
Usually they bump people from the bulk-head and offer them free cocktails.
You must not fly much now. There is a fake service dog craze where the justification is mental comfort to overcome anxiety. Flights are routinely carrying people with their pets now, right there in the rows.
It ain't Shinola.