When you find this bet, is it usually at just one bookmaker or at several that have the same odds?
You can compare the odds in different casinos, value bettors do a lot of research and they follow the sport very closely, if you do not have strong knowledge of the sport, you cannot apply value betting strategy.
If you follow the sport closely, you would be able to identify an odd that has a higher probability of success than the casino thinks. But to arrive at that, you need to do your own estimate/research and arrive at your own probability of success, if yours is higher, then that is a value bet.