The sweet spot means that the extra points changed the outcome.
If you lay -110 at a normal spread, the break even is 52.4. If you lay -241 for the extra 6 points, the break even is 70.7%. If those extra 6 points change the outcome more than 18.3%, teasing is better than straight betting. If it changes the outcome more than 20.7% (i.e. hits the sweet spot) you can bet it blindly.
If you lay -110 at a normal spread, the break even is 52.4. If you lay -241 for the extra 6 points, the break even is 70.7%. If those extra 6 points change the outcome more than 18.3%, teasing is better than straight betting. If it changes the outcome more than 20.7% (i.e. hits the sweet spot) you can bet it blindly.