I understand, but this would mean that every owner of a night or scuba cache should tag it: it would be impossible, and also there are already some attributes to indicate it that are often misused. With a tag in the logs, the cachers interested in the badges will obtain it and the tags will help identifyng those types of caches, it would be impossible to compare some statistics with other cachers who don't tag their logs, but so is for the FTFs. Probably the best solution would be a bookmark list, but it will take a lot of time and work by the community, and some caches could still be missing, with a single tag it will be a decision of the single cacher about which cache include or not in the scuba or night category..