The easiest way to know is to watch the chinese deal websites. I use those for sourcing anyway so I perform an idle search here and there. In all honesty, if you're getting cloned it's a positive signal that you have a potentially good product (at least on the higher end of the technology scale--for someone like an early-stage fitbit it would be disastrous if the cloners were capable). If you aren't able to watch deal websites, there are other pretty easy ways to track it.
It's also about the strategy of your development--you can take a few very small actions early on that will make it orders of magnitude more difficult to copy your product. But, generally, it's not worth a factory's time to clone your product, especially if it integrates manufacturing processes they don't have access too. I have this benefit because I work mainly with small factories and while they do cooperate with each other, there isn't the infrastructure or margins to allow them to do anything other than focus on building parts as quickly as possible.
It's also about the strategy of your development--you can take a few very small actions early on that will make it orders of magnitude more difficult to copy your product. But, generally, it's not worth a factory's time to clone your product, especially if it integrates manufacturing processes they don't have access too. I have this benefit because I work mainly with small factories and while they do cooperate with each other, there isn't the infrastructure or margins to allow them to do anything other than focus on building parts as quickly as possible.
My email should be in my profile, drop me a line!