Jeebus, if you don't have any new information to contribute, why even post? It's especially annoying to see a representative from AirBnB, that might actually be in a position to get the data we ask for, not even bother to understand the problem area before posting. A photo of 0.6 Mpix, as you suggested, is in no way a high resolution image. The problem all of us is facing is that AirBnB takes a high-resolution image (say of 20Mpix) and resizes it using parameters that make it look crap (probably solely chosen just to save AirBnB cpu, bandwidth and storage costs).
The problem is not resizing per-se, it's understandable that AirBnB needs to scale images down to avoid huge bandwidth costs. The problem is that the results are so crap, so people would like to fine tune it for optimum effect. From some very basic research, it seems that the max horizontal resolution is 1440px, which coupled with the tips from AirBnB on using a ratio of 1.5 (1024 x 683) would set the max vertical resolution to 960.
The best case would be if the AirBnb service would skip resizing given that the image was beneath a certain file size threshold and the max resolution. That would mean we could upload 1440x960 images directly without any alteration, fine-tuning the quality parameters for the file size threshold. I remember that Facebook's image upload used to work like this in past, so if you knew what you were doing you could bypass the quality deteriorating resizing process and get far better looking photos.
I realize the site is not Flickr, but people still should be able to get the basic info on how to get their photos looking their best when prompted.
