whats it usually mean "sharp" wise when

a line opens -7/-350.... closes -7.5/-305

what sport?

Whats the vig?

i think youre talking football and it means theyve grown more confident in the favorite for whatever reason but they still expect a closeish game. huge difference between 7 and 7.5 in football.

favorite likely wins by one score exactly in their estimates.

odds pools and ML pools are seperate so even though the favorite is 45 cents cheaper in the second example they are a half point more to cover.

In this case it more than likely means more people thought they would win by 7 or more and willing to bet that than they were laying -350 and needing them to just win SU. Or it could also mean that the public was all over the spread, and the so called 'smart' guys were all over the dog at +320 or whatever.

It means all the kids who took the 7 are going to push and all the kids who took 7.5 are going to get burried! So played the 7.5 dog!

Always bet the line that will cash your bet..not the line that looks sexy but doesn't cash a bet.