We are in an exciting phase as our database becomes more and more accurate with the scrutiny & insertion of images at species, genera and family pages.
Initially images were inserted from a few threads & it so happened that images were not correct. So I decided to go through all the threads in a species page & try to insert at least a few images above each of them. During the process, I find that images in some of threads look different (naturally they are from a different species unless there are lot of variations in that species). As I repeat this process for other species in a genera, generally identity of wrongly identified posts becomes clear & I accordingly resurface them with correct id with the intimation to the posted member & the members who have participated in that thread to ensure that I get feedback from them, if they feel otherwise. These are further reviewed accordingly. Of course, sometimes matters get very complicated and I have to refer to the keys in the floras & books available in the net along with our discussions & keys therein.
Simultaneously I insert images at genera pages from where it becomes quite easy to compare different species. I have started keeping images from different threads separately so that if any misidentification is noticed in any of the threads, it is accordingly rectified. One can see one of our latest pages at Pogostemon.
I also check images at Flowers of India site and point out mistakes to Tabish ji and get his additional feedbacks.
Sometimes some of the images are from other genera, which I try to correct as I progress from one genera to another in that family. Also there are lot of threads which had remain unidentified, I also try to give correct identification for these. 
By the end of the process, it is a great feeling of becoming an expert on that genera at least for those species which are in our database. I think this is possible due to the insights of the experts and members which we get in the threads. Multiple observations help a lot in that matter.
I do not know what is the process followed in the herbariums. But I see there are corrections from time to time in many of the herbarium sheets we use for identification of our species.