I shall say exactly what I think of the photographs as they appear to me. This may result in the photographer not exactly appreciating my remarks but I will endeavour to state exactly why I do not like something and just as importantly exactly why I do like something. If I offend, please be assured that I do not make personal attacks and if I say unflattering things they are are not a reflection on the photographer.
I would hope most people think honest crit is a GOOD thing... However, delivery is important. This is an online forum and all we have to go on is words on a computer screen. There's no facial expression or tone of voice to help us. So when leaving negative crit, it's a good idea to try and do it in a nice way. Make the person on the receiving end know that you have read their own thoughts on the photo and that you have taken all the facts into consideration. (This is not aimed at you Martin, just to be clear!) They're much more likely to listen if they're not so focused on defending themselves.
Sometimes people will get defensive and there's no way around it. If you're passionate about your photography, it's not easy having your work ripped to pieces, even when the comments are justified!
Andy put it well:
I always try and start with the good, then move onto the bad, then finish of with suggestions of ways to improve, even if it's something as simple as, "Have you thought about returning in better light?", or "How about a vertical composition". It's call 'crit sandwich' or something like that.
This is not a competition and even if it had been, I don't think many of us are actually qualified to judge photographic competitions. Sure, we are all entitled to an opinion, but aside from a few technical points, there rarely is a right and a wrong. Especially if we are talking about things like artistic elements. I would never dream of telling a fellow photographer they are devoid of any artistic talent, even if that was what I believed in my heart. Why? Because that would only be my opinion. Who am I to criticise their talent and ability and potentially ruin the joy they get from taking pictures? This I have no right to do.
Having said that, I do think some people are overdoing it on the nice... And not just a little. Maybe because they are afraid to offend or maybe because they do not want honest crit when it comes to their own photos. I can think of a few examples where a really poorly executed photo received plenty of positive only feedback... I know it's up to each and everyone of us to set our own rules, but is it so wrong to expect the photos to be properly exposed AND sharp (for screen size, this is not hard to achieve)? If these two basic requirements are not met, I couldn't care less whether it is on theme or not. Also, IMO, sometimes people get so caught up in shooting to a theme they forget the photos are supposed to be nice to look at too. Oh, and something I've found to be missing a lot of the time is some sort of description to go with the image... I did this because, I like x, not so happy with z because... from the photographers themselves. This was much more common in 2012 for some reason.
A little nudge to people receiving feedback... While you have every right to disagree with the comments you get, it starts to look quite bad if you always dismiss or flat out ignore any negative comments given, always assuming that you are right and the other person is wrong. I don't think it's necessary to respond to every single comment, as many will be similar and you can type out a general response, but if someone asks a question or offers specific advice and tries to help you, the very least you can do is acknowledge it. I say this because a few times when I have tried to help, I've been shot down immediately. For people claiming to want constructive criticism, I find this behaviour strange.
I may not be in this officially anymore (unofficially, I'm carrying on) but I'll be following/commenting on small bunch of peoples' photos for the remainder of the year.