USDT is on a major exchange and that means USDT is trusted by everyone so it can't be a scam. besides USDT is widely used by everyone to secure assets when the market is red.
Usdt is also listed on non major exchange . It's hard if will based on exchange to say that a coin is trusted or not . Usdt is not a pure breed of crypto and there are people that won't trust that kind of coins but for some it's not really a big deal , as long as we can see them being paired on crypto and most feedbacks are okay , we don't doubt on them .
Many simillar coins that have same concept as usdt but as of now usdt ranked first .