A lot depends on the product. A custom object often requires an advance raw material deposit and even progress payments as the item is made. On the other hand a mass production widget by a start-up can legit use a fund me campaign. That said, there have been some fund-me fails - some were frauds, some were mangled management - each case differs. Then there are the stock frauds via booked sales counted as true sales. There is also the copy risk = you debag the cat, and someone else with $$ makes it and Amazons it = you are cooked. Sometimes you have some protective IP to prevent this. In many cases you both need to know each other to form a basis of trust you are both happy with. So you see the many shades of gray.

Pre-sales are insulting to your potential customers. You never get a product before you pay for it somehow, why should they give you money for a product they don’t have? Whenever someone is advertising a product that is being “pre-sold” I immediately discard it and never look back.