I find hashtags very useful when looking for things on the gallery, but I know there are very few people who use that feature as much as me, haha. If I want to find something in a modern style, I'll search #modern. If I want a farmhouse, I'll try #farm, #farmhouse, #barn, etc. This helps me find things that would otherwise be buried in the mess of the gallery.
I hate that you can only search by "Most Popular" and "Popular Now," because I prefer to download newer things (within the last year or so), but not necessarily within the one week time-frame included in Popular Now. Hashtagging effectively helps people like me find those diamonds in the rough :) One thing I've done before is searching for #glassroof and #skylight/#skylights, because that ruled out most things that came before the Seasons update!
It's true that people use waaay too many irrelevant hashtags--especially for sims, I've found. Obviously, using ones that don't apply is blatantly self-serving, but there's nothing wrong with a long list, IMO! You never know how other people's brains are going to work in terms of the word they decide to search, but if you enjoy sharing your creations, it's probably best to think of as many as you can that make your build unique :) Is there a greenhouse? A pool? An art studio? Sometimes I use hashtags like that in my builds in case someone is looking for a home with a specific feature, but isn't as tied to the style. Just some thoughts; obviously, do whatever works best for you!
