Blowing it off with an air can held at least 8" away should be enough. Unless you live in a very polluted area (like right behind a fry stand or an autobody shop) their shouldn't be any scum on the lens.
Yes, Ive wiped them off with a Q-tip moistened with eyeglass cleaner (doesn't have ammonia) or alcohol, but be very careful. Do not apply dowmward pressure, just kind of "swipe" the surface in one direction only, not back-and-forth; and swipe immediately after with a dry Q-tip to remove possible streaks.
Yes, Ive wiped them off with a Q-tip moistened with eyeglass cleaner (doesn't have ammonia) or alcohol, but be very careful. Do not apply dowmward pressure, just kind of "swipe" the surface in one direction only, not back-and-forth; and swipe immediately after with a dry Q-tip to remove possible streaks.