In the last days I mailed a lot of people about unusual values in their fire_hydrant tagging. The most important one was fire_hydrant:type, where some more or less unique values are already gone and replaced by the more common tagging. One nice thing were 3 things that were in fact no emergency=fire_hydrant, but emergency=water_tank. But since the original contributor was unsure on how exactly to tag these things he added an image tag to each of them, showing a photo. This way I could easily point him to the right direction, and as a nice side effect one of these images can now be seen on the wiki page for emergency=water_tank. Until now I only mailed those people that I was rather sure to understand either German or English and left out the Russian, Spanish (could also be Portugese or Italian, no idea), and French ones.
In the process of cleaning things up I learned that the New Tags JOSM presets, which I didn't know about before, introduced wrong tagging. It wrote the German names to the tag field instead of the English ones. Since this isn't exactly a new tag and JOSM already has a working template for this, I simply removed emergency=fire_hydrant from this presets.
Today I made the mistake to look into fire_hydrant:position values. This is probably unusable for any automated application, at least outside of your local clean area. There is a huge amount of inconsistent tagging in all sorts of languages. If I were really bored I would try to get clearance for a mechanical edit and would at start with deleting every fire_hydrant:* attribute that has an empty value. But sadly I'm not that bored, so any volunteers are welcome.