Quite shocked by your comments... As you say, you got lost coming out of the subway counting on (Hidden by Airbnb) even though we always send a map to our guests specifically for them not to get lost... The subway station is perfectly clean and safe - no one ever complained about safety in the area. We have had many single women guests who never felt unsafe, quite the contrary, and there are many families, kids and women on our sidewalk. Not withstading our building hosts a large Police station/center!
One point where you are right is exiting the subway is a bit of a mess (hence the precise map) for the city is building a Tramway, which comes with unavoidable road work. It will be a great improvement soon to be completed. You are also right in saying Montmartre is gorgeous and it is part of our neighborhood. But then, it is not Beverly Hills, for paris is not Los Angeles.
As to the Flea Market, it seems you didn't go further then the little market which borders it, an extra 3 minutes walk, passed the underpass, would have led you to the actual Flea Marker/Marché aux Puces which is probably the most renown market for antiques in the world, with quaint streets which antiques and art dealers who come from all continents spend he entire week-end to make incredible finds, enjoy its quaint alleys, atypical restaurants, and much more.
Last but not least. I lent a portable usb fan to your extra guest and the next morning, as the room was being thoroughly cleaned as always, it was no longer in the room... anyway...
Difficult to understand your final comment "the room was great if you're just going to be out all day" ... All previous comments vouch for the appreciation our guests have for their room so much so they often extend their stay. The rooms are large, quiet, luminous with a balcony (which is rare in Paris), but yes, I agree, a patio would be even nicer. But then again, this is Paris, not Los Angeles (though we've had quite a few guests from LA who loved the place) - To each his/her own and sense of appreciation.