Never owned one and never will because I do not like the picture of OLED. I like the more vibrant, brighter picture of QLED and most of all I love the prices.
Dirty Screen effect is random. It is something that can happen depending on panel lottery. It is not something that a person is guaranteed to have. When buying a new LCD you can simply go to YouTube and run a DSE check on your TV. If it has DSE then return it for another. I would rather worry about DSE anyday over Burn In because I can just return the TV from the start if I have DSE. Cant do that with burn in since its something that will take time to happen. See the post above this one for example.
I have a LCD that I watch at an angle mostly because it is in the living room and I am always sitting at my pc in the bedroom. If you watch at an angle then look for a tv that has good viewing angles.
Blooming is depended on the performance of local dimming. Buy a tv with good local dimming if you want to avoid blooming.
If you want the best accurate color then check your tvs color ratings on sites like RTINGS. You will find Out Of The Box Pre Calibration ratings and then you will find Calibrated ratings which is going be be best.
TVs have gotten to the point where they are product that you have to research and know about. The days of just walking in Walmart and buying a 32 inch Sharp and coming home are over.