Storenvy

Answer: Just like Etsy or Amazon, Storenvy isn't a single seller, it's a site featuring shops hosted by a network of different sellers. My advice would be to check out the information on the page of the particular seller you're looking at. Look at their feedback and their shipping timelines, and that should give you a better idea of what to expect. Most of the sellers there are fantastic, but it's always best to do research before buying from a new person :)

Answer: Its not "technically" a scam, its just a website with a bunch of people who put up stores. The problem is many of those people are not good at running a business (and the individual store owners might be scams or might not be) and the company "storeenvy" takes no responsibility for their actions. You will have better luck on EBAY or AMAZON because there is buyer protection and actual customer support. StoreEnvy is not a 'scam', they just suck.

Answer: Your best bet is to pay close attention to the reviews for the seller. Much like Amazon or Etsy or eBay, each seller is responsible for their store and the things they sell in it - which means some things are going to be fabulous and some won't be. So check the reviews and make sure you know that the seller you're trying has a solid reputation with their buyers and consistently delivers a good quality product.