(A) Most surgical wounds take about ten days to heal- This just reiterates, does not weaken the claim.
(B) Most surgical tape is purchased by hospitals and clinics rather than by individual surgeons- This statement is irrelevant
(C) The currently used tape's adhesiveness is more than sufficient to hold wounds closed for ten days- This weakens the claim of the sales people. According to them, "Newtape will improve healing because Newtape adheres twice as s long as the currently used tape does", albeit, the maximum time such wounds need a tape is 10 days. Hence, if we know that the currently, used tapes is sufficient enough for 10 days, then, the new tapes might not provide better healing effect due to longer periods of adhesion.
(D) Neither Newtape nor the currently used tape adheres well to skin that has not been cleaned- Irrelvant.
(E) Newtape's adhesion to skin that has been coated with a special chemical preparation is only half as good as the currently used tape's adhesion to such coated skin- This actually contradicts to one of the premise though it brings in an extra variation (coated skin).
To find what you seek in the road of life, the best proverb of all is that which says:
"Leave no stone unturned."
-Edward Bulwer Lytton