It makes me laugh it really does.
Oval poles will wear quicker and bind up on the edges.
This is because there is a smaller area of diameter to take the wear, this concentrates the wear in one place more than the other.
Oval, triangle, box section, in fact any shape that has edges is a bad choice for a pole in terms of wear, as the sliding action will quickly bind up.
Why do you think that pistons in an engine that slide up and down in a cylinder are round?
They tried oval pistons once, didn't last anywhere near the time of normal pistons do.
Honestly there is so much rubbish out there for window cleaners to buy, its embarrassing.