Value is all relative to what you can get, when you can get it, and where you canget it.
Comparing numbers to your own numbers really isn't value. Even if you are a 60% capper (which is highly unlikely), you will still be wrong 40% of the time. So it is safe to assume your numbers will be wrong 40% of the time. And even the most professional bettors have "pet" teams, and with these teams there will always be some concessions given.
Sometimes value is easy to spot, sometimes it isn't.
Here is an example:
This past Lakers/Spurs series. The opening numbers had LA favored all the way from -165 to -140. With SA being anywhere from +135 to +150. While there was instant value simulataneously in scalping this number, the bigger value lay in taking SA +145/150.
Considering they were going to be favored in 4 of 7 games makes that a no brainer. So anyone willing to bet LA to win the series needed only to bet them on the road. Since to win the series they had to win a game on the road, where they would be a dog. So there was no need to lay -150. Even if they had won all 3 games at home at -250, they were still going to be +135/140 in SA in game 7.
Series are a little more copmplicated, but all I saw was how people thought there was value in LA -150/160. Even if you thought they would win that series 8 out of 10 times there still wasn't value, because sooner or later they would have to win at PLUS odds, so LAYING odds on them was not "value" it was not smart.
As for comparing books numbers and trying to get a barometer of value. If most people think like some say, that Pinnacle has "unbeatable" numbers, then they don't even offer value. Even if they are 12-15 cents diferent.
I don't buy into the whole "sharpness" of Pinnacle, but if it is true then bet the most "off" number you see from them. This is a little off the topic, but not really. If you truly think Pin has the best number, use them as you market number, and go from there. If everyone has Yank -145 at Bos, and Pin has then -138, then look to find the best number on Boston out there, and bet Bos. I would never do this, but some guys swear by it. I haven't tracked every single line, but I know Pin is about 55/45 on "opinionated" numbers. So they are a little "sharper", but that can be attributed to their odds system, they move numbers a lot more frequently, and a lot more precisely. Who is to say they are the only "accurate" book, and the others are hedging, or even moving on air to keep pace.
That is why it is difficult to compare and contrast. Basically value is finding the best number avaialable on a side you ike and usinng that number.
As for the whole laying huge odds, there is sometimes value in that. If Yankees played Det all 162 games, and Yankees were -400 every single game and still offer value. Because Yanks would surely win more than 80% of those games.
Basically all of this can be summed up like this, as long as your odds outwiegh your expected returns, then you have value.