PHILIPS HEPA Air Purifier 800 Smart Series

Since I was new to the world of air purifiers a lot of time was devoted to researching them and what I found out, mostly thru customer reviews, that deciding on one is a crapshoot. But, deciding I did. The first one was a well known and established brand that seemed to work fine but the power button that doubled as the Mode button was nothing more than a very small raised, non-descript circle in the top of the unit and of the same color as the top. I had to "feel around for it" bc it was invisible. It was returned for a refund. This Phillips 800 Series was chosen for several reasons: brand name, customer and media reviews and it had an AUTO mode which was a priority for me. When it arrived I found it to be well-built, pleasing to the eye and set-up was easy and took just a few minutes. Plugged it in.....music to my ears: quiet, ran smoothly and did what it should have. Except AUTO. To judge that I had to wait for an event that would engage it which after a while did happen when my cockatiel, who like all cockatiels is a treasure chest of pet dander, went for her early evening flight and "boom" AUTO mode engaged in full force. Happy, happy. Less than 2 weeks later the AUTO sensor quit, actually it engaged when it felt like it, but mostly it quit. No amount of cockatiel flights, pillow shaking and incense burning brought it back to where it started. It was returned this time for an exchange. There was enough to like so I gave it a 2nd chance. Before I continue, I need to say that anything I order on line gets closely looked at for "newness". Too often have I come across reviews that a used/refurbished item was sent when a new one was paid for. So, when I received the 1st Phillips it, the box and packing materials were closely looked at and all was well. It was a very different story with the replacement. The box looked old and tired, corners curled up, lines not crisp and upon opening it, the flaps had obviously been opened and closed a number of times; there was no slight resistance which, everyone knows, even a cereal box when 1st opened will give that slight, "I have never been opened resistance". The box the adapter came in was dented, the cord had been rewrapped an retied, the owners manual was dog-eared. But worst of all, the inside of the unit was dusty. The filter however was brand new, in a sealed plastic bag. This unit was used or refurbished! What to do?! Sending it back for a refund means starting all over for a 3rd time. I decided to leave it up to the AUTO mode sensor which did come on briefly but at half the fan speed the 1st one operated on when my cockatiel took flight. Oh, btw, neither machine's sensor engaged to the horrible burnish air pollution smell that is present here almost every evening nor did a burned grilled cheese sandwich set them off. Even in TURBO mode the smell did not go away! This one will be returned for a refund and I find myself back at square one.