I had a cll from a customer today to seal the down pipes on some gutter.I asked her why as most gutter are fitted with out any sealer. She told me the the windie who cleaned her gutter just washed all the silt/grud down the down pipe with a hose pipe .When |I removed the down pipe it was full to the brim. He said it was overflowing because its was not sealed with silicon.
Its amazing what some get away with.