Your average punter Wouldn't know if it's 300 lumens or 3000, they just know it's a lot brighter than the 30 year old maglite.
What can be compared, is a device' ability to dissipate heat? If it looks feable compared to the claimed output then be sceptical. However it has to be said, the Chinese stuff offer's great value, even if the light outputs are nowhere near their claims.