Is it possible to tag all buggy levels (those based on different "known" bugs) so people can avoid "waste" time playing with them if they don't mind to discover or practices game bugs?
Define bug? There are a multitude of quirks in the Mekarama physics engine. Some would would call them bugs, others would call them features. Some are more unusual than others. Until Martin releases an official list of what he considers to be "bugs" it can be truly difficult to characterize what a bug is or not. Keep in mind too that if Martin makes even the smallest change to the physics engine that many existing levels will likely no longer work... which would be a be a real headache for level creators.
Well, yes I can agree. But there are some bugs like ghost, flying, teleportation, explosions of pieces, etc... that are not quirks. Those are directly not logical physics. The issue I see is that many players are getting bored of "regular" levels because it is true that innovation is not easy and they are concentrating in design the most complex and tricky (based on bugs) levels. I understand although I disagree. That is the reason I was asking if it is possible to tag some how so all players can be happy. Players who just want to enjoy innovative but not buggy levels can avoid "waste" time with a not real level. That was my point...
The problem is that tags are completely voluntary. Until there is a way to actually enforce the use of tags on this forum I think your request is going to fall largely on deaf ears. Some creators will certainly be courteous to label their level as containing a tag with the term "bug" but I think few would do so willingly as there is a stigma with that term. It's kind of like putting "criminal record" on your resume... if you don't have to why would you do it if it may scare people off? From what I've seen and personally experienced, creators usually spot some unusual behavior when either testing their own or playing others levels. They then try to incorporate and expand upon that weirdness to create a new level. It's not at all laziness, it's an active exploration of the problem space. It's actually quite exhilarating to discover some new behavior and try to exploit it. I personally really don't care for the extreme physics engine quirks either. Unless it's well reviewed, I'll generally avoid levels made by creators which frequently utilize these "bugs". I also avoid these extreme quirks in my own creations out of concern that Martin with fix them one day. Most of my levels utilize a lot "tricks" that many may consider to be minor bugs (crush lifts, focus lifts/drops, etc.) and I'm not about to label these levels as having bugs.
I understand that there is no way to automatically force such tag (it could be "tricky" instead of "bug"). And I also agree with you that there is a lot of and different opinions about what is a bug and it is not. I think it should be just a etiquette pushed by moderators. But that's all. It was just an idea... if moderators detect levels with let's call "real" bugs, comment it should be tagged... and polite users will do in the future.