I definitely get where the OP is coming from, but I think there are a few things I've noticed and I have a few comments I feel are worth noting.
IMO It's seem that it's usually the new detailers or first time posters of before and after threads that don't have direct light before/after shots. As they become more aware of how a write up "should look", they learn to capture correct after shots. There is nothing wrong with that IMO and a simply polite reply in the thread suggesting they capture direct light shots on their next job should suffice. Off hand I can't think of any seasoned pro that doesn't show proper before and after pics.
The direct suns not always available, period. If that's the case then other forms of direct lighting should be used, the more the better. I can honestly say very few of my threads have direct "sunlight" shots simply because of the location of the sun when I tend to finish my cars. I will use 2 or 3 other forms of lightning though. I only detail on the weekends and it's almost always late in the day on Sunday when I finish. If the sun doesn't shine on the clients car from my driveway, then so be it. I'm not going out of my way to drive their car around the block just to get sun shots.
Al mentioned actions shots. I don't doubt for a second that 99.9% of them are staged shots with a timer, as I take them myself from time to time. The key there is what does the photo show? Is it just a pic of polishing paint or is it an illustration to show others how to tackle a certain task that they may not have thought of? If it's the later then is there really anything wrong with the fact that it's a staged image?
I strive to make my threads as informative as they can be to help others. Obviously it's also a form of advertisement too, so also have pretty after pics is helpful for potential clients.
If people are intentionally manipulating their pics to deceive others, they are only hurting themselves.
At the end of the day we all have the choice to view which threads interest us. If you click on it and it's not what you're expecting then it only takes a second to click the back button.
Just my $.02
rasky