Mine is really how confusing some of the language is. It's difficult to know how to hold a club when books say to have about as light a grip as you can, but people tell you that your grip is too "weak". Really; who came up with "strong" and "weak" to describe "rotated clockwise or counterclockwise"?
Seeds on the green? That's so horrible I'd never come up with it. That's even worse than people who seemingly intentionally play slow.
My wife has started playing the Evnroll putter (ER6) a few weeks ago, and she is putting far better then with her Ping Mallet putter. A buddy of mine, at the club, also has the same putter and loves it. Her distance control on long putts is far better, although as @Divotmaker77 mentioned, not sure the shorter putts are way better, but her longer putts are getting closer and it gives her a better chance of making it, rather than previously she would never get close enough to have a chance as often.