Whatever your positive experience was, please mention it! For example, we like the fact that Sidestreet Boutique is an independent, bricks and mortar store located in Tahoe. We also like the fact that parking is usually easy. Whatever you like, please mention it!
On Yelp, second-hand reviews get deleted, so don't bother posting "I've heard they sell fur so I won't go there." Only post about your first-hand experience.
Don't leave 1 star reviews unless you had a purely awful experience. As infuriating and upsetting as Sidestreet Boutique's behavior is, most of us can agree that there are at least a couple good things about Sidestreet (e.g. it's physical store + it's in Tahoe). In general, the lowest should be 2 stars.
Of course not — people visit Tahoe from around the world. As long as you've been to Tahoe and walked into Sidestreet Boutique (even if you didn't buy anything), you can post a review about your experience/observations.