It all comes down to confidence. If your shooting one hole groups with a tasco on your weatherby, then its a moot point. But when you get groups that show flyers, you start questioning your scope. Now if you saying that the leupold isn't clearer than your tasco, then something if wrong with the scope or you haven't focused it right.

Try a test. Do a box test. With your tasco zeroed in, move up 6MOA, shoot another group, then move to the right 6MOA, shoot another group, then down 6MOA, shoot another group, then move back to zero by moving left another 6MOA. One, see if that tasco is back to zero, two, see if it moved up an actual 6MOA, and over. Usually the quality of a scope shows thru at this point. Next, try setting the tasco to its lowest power, and shooting at 100 yards, then up to its highest, and see if you have the same zero. I have yet to have a problem with these two tests with a Leupold, but have had numerous problems with bushnell, BSA, etc. I have had simmons that have not stood up to the recoil of my sluggun with the reticle falling.