A unique selling proposition is simply the one thing that makes your product better than the competition. You can be a pioneer or an innovator like Steve Jobs disrupting the mobile market with the iPhone. He made the latest phone model (at the time BlackBerry phones) and improved it by like a factor of 50x.

This innovation is a different level of thinking but one can still make major contributions to the market you're in by selling something that is entirely different (but functional of course) or by improving upon another design.

A way you can check for faults in a product is by buying it yourself and testing it. Or you can check out what the consumers are saying by checking reviews on Amazon for example.

Use this as ammo to load up your ideas to make your product idea much better and use this difference in your marketing material as well.