Question About Combining Lines

[KeithF40]

Im very new to sports betting so please bear with me. Ive been looking at sports money lines and see that when you combine lines between two different books and get lines of -200 and +250 for instance where magnitude of the positive number is larger than the magnitude of the negative number its flawless where you cannot lose money but I think that this situation is probably very unlikely and if it is not very unlikely please let me know. What I was thinking is that by combining lines from different sites is there a way to give yourself a statistical advantage over the built in juice within the money lines. Please provide as many specific real life examples as possible as I feel that if this is true it could be a very lucrative way to bet on sports.