Christo, yes it's a free forum, but there are guidelines and bounds that members are to abide by, and the forum has moderators to ensure that they are adhered to within reason. Now the guidelines on the photo critique forum are quite clear and probably worth restating here for reference:
This section is nothing more than a sub-category of the 'Post Your Photos' forum, and is intended only for use by those who wish to receive serious critique on their photographs.
Comments in this section should be along the lines of, "Changing x and y would make this photo much better, and z doesn't help much either" rather than "what a beautiful flower, thanks for sharing"
While harsh commenting is allowed in this section, we ask that all users act in the usual respectful manner when commenting on others' photos. Barely any photos are perfect, so please use this section to discover the weaknesses of your photographs and to improve them in the future.
(from
https://www.pentaxforums.com/forums/photo-critique/14010-about-photo-critique-section.html)
Critiquing not only helps the person who's picture is being critiqued, it helps you produce better pictures. Please don't just say that you like a picture, it may make the photographer feel good but it doesn't help them take a better picture.
CRITIQUING GUIDELINES Form and Narrative: This is how the image speaks to you. Is it just about shapes and lines or is it telling a story. What is the subject of the photograph? Where does your eye start and stop when viewing the photo? If there are multiple subjects, does that make the photograph more interesting or do they create a distraction? Did the photographer follow compositional conventions like using the rule of thirds? If not, were the rules broken successfully? Do the elements like contrast, leading lines and diagonals take the eye around the whole image, or is there wasted space?
The Background: Is selective focus or depth of field used in the photograph to blur the background, is it effective? Does the background work well with the subject of the photograph?
Technique: Are the elements that need to be in focus, in focus, is the focus sharp? Do the areas that are in an out of focus work together, should more, or less be in focus?
Attention to Detail: Are there dust spots? Is the horizon tilted? Are their elements around the edges of the framer that are cut off or distracting?
Response to the Image: How does it make you feel? Do you understand what the photographer is saying to you?
(from
https://www.pentaxforums.com/forums/photo-critique/86356-example-guidelines-critiquing.html)