I've had a reviewer tell me that it would be hard to get to the waymark since it is in the middle of the Atlantic Ocean. I think I had copied the minutes and seconds for each but did not enter the degrees for either one. This person had actually accepted it with the note to correct the coordinates.
There is also an issue for waymarking in cities - the canyon effect - where if you get a signal at all, it can be some times blocks from where you actually are. I've corrected ones that are really off but have tended to keep the ones that are off but within sight of the waymark. So, on a Google Map or another map, the WM may not be on the corner that it's supposed to be at.