Natürlich, we all love bug keys, but the tool has its own difficulties due to its mechanical nature.
The waveform observed directly at the contact when sending three dots.
The first dot enlarged five times in time scale.
Because there are many circuits involved, you can not exactly estimate what you hear, as a side tone, or what they hear through their receivers from only the waveforms shown above, but undoubtedly it is one of the main factors.