I missed this thread somehow. I should pay more attention.
I have noticed over the years how those who deep themselves somewhat knowledgeable in a craft such as photography willingly present their critique or criticism (or whatever you like to call it) whether it has been solicited or not.
I see this quite different to the 'like' that we often flippantly utter when we see an image that appeals to us for some reason, even if its just to appease a pleading student or connect with a good friend.
For those who seek criticism, so be it. Take it as it comes. Some, like me, can be blunt and to the point but that's usually because we are in a hurry, lacking social skills and don't want the perpetrator of rubbish to miss the point.
But there are some, again, such as myself, who do not seek criticism. The motivation for this is personal. It has nothing to do with ego or arrogance. It has to do with why we photograph. I, personally, do not photograph to please others, only to share my experiences. I se them as a part of a conversation; filling in the missing bits. As with a conversation, we are less concerned with grammar and more with content. We can be sloppy in our pronunciation, stutter and stammer, be repetitive, shout, whisper, laugh at our own jokes, choose to be politically incorrect, blaspheme, stop midway and change the topic, interrupt and talk over, under and in between others. We accept this among friends, relatives, acquaintances and even enemies. The last thing we expect is someone telling us how to pronounce a word or not to end a sentence with a preposition. In fact, its usually a good way to end a conversation.
I like sharing photos. I like looking at other people's photos. I have taught myself to avoid being critical when casually looking at photos. If someone asks I give my opinion quick and sharp, but only when I am asked.
That's just good manners.