It's the same in any forum. You only need to look at some of the stuff on here that gets the old 'nice shot' type comments when often they are clearly poor shots for a number of reasons.
Sometimes folk can't even take positive criticism and advice on how a shot could be improved and see such as a personal slur.
For me forums should be a place of learning and improving but too often it's just simpler to say good shot, boost your post count and move on. IMO this is just lazy, poor form and helps nobody.
It's just the nature of the social media age I suppose.
So, what do you recommend? And I genuinely ask this question. I'm an amateur. I don't necessarily feel qualified to critique another's photo. I view the forum as partly social and as a place to learn from those who are more knowledgeable than me. If is see a photo I like I say "nice photo" or "like" it. When I can verbalize it, I say why. Should I respond differently?
No not really. I think it's important to an extent to explain why you like a photo but often if it is indeed a good picture then it can simply be self explanatory by viewing the shot.
More importantly though is if you are going to comment on a bad picture, rather than just saying 'not good, 'that don't work', 'rubbish shot' etc etc is to explain why the shot is bad. Lets face it many bad shots are bad because they are bad and I'm not talking opinion here. They can be technically, compositionally bad, under exposed, over exposed, too high/slow a shutter speed, poorly focused etc etc the list is endless.
My issue is when a clearly substandard picture gets 'nice shot', 'good work', type comments when no reason is given for why a bad shot is liked. More importantly tho is if your going to comment on such shots, then imo constructive crit is the way to go with a view to explaining to folk how to improve a shot. There are however, some shots that are just fit for the bin but advice can still be given as how to approach such a shot in future.
I'm not sure about the rules etc on this Forum (MODS may like to clarify) but going by other photography Forums, it is the case that unless you specifically request for a photo not to be critted (ie posting in a 'Just For Fun' type sub-forum or with such a pre-fix) that any picture posted is open for criticism, good or bad.
You'll always get those who just repeatedly fire up 'Nice shot' replies to both worthy shots and to complete dross purely for the purposes for boosting their post count or appearing to be Mr Nice Guy, as if a higher post count gives them some sort of greater standing on the Forum. It doesn't, is a fail on both counts and wastes a lot of peoples time by having them believe that a crap shot is decent.
As I said before a lot don't like having issues in their photography pointed out to them, spit the dummy as if it's some sort of personal dig but those willing to learn and improve will take on board advice given and will indeed learn and improve.
Positive, constructive criticism done in a helpful way and not bland, dishonest and unhelpful comments are the way to go.