Bests & Worsts Reviews from Amazon

Boncare sent me a $10 gift card obtainable upon and only upon reviewing their thermometer. What sleaze! I have reported them to Amazon. This thermometer also seems not to be accurate. For instance, at the moment, two other digital thermometers that aren't the same brand but were both bought in store at Target, both say my temperature is 98.2, my Boncare thermometer ranges between 98.8 and 99.2, and my good old fashioned trustworthy mercury thermometer says it is 98.9. Boncare sometimes agrees with the mercury thermometer and sometimes up to half a degree higher. But, what's with the other two both saying my temperature is 98.2?