Why are there some "Tagme" tags on some images, some don't have them.
It's probably images without tags but the "tagme" tag remains even if you put some tags on a pic.

There's a short discussion about this somewhere else, although I can't point you to the correct thread -- sorry. I think it boils down to how well an image has been tagged. I believe that "tagme" is a default tag on new images (somebody correct me if I'm mistaken about that, please). The mods aren't going to remove "tagme" until an image is tagged well enough to reasonably identify it, and just a few tags like you're seeing with a lot of the newest influx of images, just don't cut the mustard.

tagme is there by default whenever you post an image. You can remove it yourself, but only if you think the image is sufficiently tagged.
Generally, I remove 'tagme' if an image has the name of the character, the series their from, and any other enviromental(setting of the image, character position, etc) and appearance/body type tags (besides hair/eye color) that apply. If I don't know the character/series, like if it's just a random game CG, I put the hair/eye color, body type, and enviromental tags in, and usually remove tagme.

The tagme tag is added whenever you have less than X tags on an image. Tagme can be removed when there are, I believe, 8 tags other than that one on the image. Earlier images do not have tagme on them because this function was added in an previous version of Gelbooru's development.

Is there a way to search for images based upon the number of tags they have? If not could this be added relatively easily? This would be a great feature for someone who has some time to burn. I could, for instance do a search for "tags<5" for instance, and get a list of all images with four or fewer tags, and then go on a tagging marathon until the pizza and beer runs out. OK, scratch the beer. When I get a half bottle of the stuff down you won't recognize any of my tags, but you get the point, I think.