I agree wholeheartedly, Eric! There is definitely more than a hint of the user/member popularity thing going on in the Digital Photography competitions. Also, as I alluded to earlier, many who have been around a long time know that so-and-so may be an outstanding photographer and his or her image is crackerjack but that he or she has pretty clearly expressed in the past how they don't like winning and judging, so when it's time for the judging, it is not unusual for someone who might have under normal circumstances been the winner to be in second or third place on the virtual podium. Or in second or third place on the podium when there are other entries which really would have deserved those spots. Also there is a tendency to choose someone as the winner who has not won before, both as perceived encouragement for his or her efforts and to artfully take care of the issue I mentioned above......
In the POTD thread, I think there is a tendency to hit the "like" button on pretty much all of the daily submissions regardless of their actual quality in order to not hurt anyone's feelings and to attempt to encourage them to keep shooting, but this doesn't do anyone any favors if they are really not showing quality work or they could benefit from someone making constructive suggestions. Kind of like "give every child a prize because he or she participated," approach rather than really helping the participant by withholding a "like" because the image simply did not pass muster. Most people would have the sense to realize that, hey, if these other images are getting 15 or 20 "likes" and mine is only getting 2 or 3, why is that? Maybe I need to improve my technique and skills?"
Of course each image is viewed both objectively and subjectively by the photographer and by those seeing what is on display. To a certain extent, obviously those who have more knowledge in the first place are going to be able to recognize how an image could be improved and perhaps have the tools to do so, but those just starting out aren't going to have that awareness and probably not those tools. Since MR is not a photography-specific website and forum and the Digital Photography subforum is only one of many subforums there, the general approach has been to be lenient, and critiques are far and few between.