When the 8 steps preying mantis master Wei Shao-Tang taught his class in the new park in Taipei, Taiwan back in 1980, one day 2 Zimen guys visited him.
- One Zimen guy bowed to him,
- Stepped in,
- Punched on Wei's chest, and
- Stepped back,
before Wei could even raise his arm to block that punch. The whole attack had no "telegraph". The "punch" and "bow" were integrated into 1 move. The punch started from both hands dropped next to the knees. That challenge made the Zimen system very famous in "speed" in Taiwan (the preying mantis system is famous in "speed"). That was why it pulled me into the Zimen system and caused a lot of problems (but that will be another story).
Not saying the punch was not telegraphed, but without seeing it myself I could think of the following reasons why it might appear so at first blush.
1. I know few who would expect someone to integrate a bow with a strike. So the appearance of a lack of telegraphing could be a result of surprise rather than the absence of observable movement.
2. Depending on your position relative to the striker and the relationship between their how and the strike, some cues could be concealed by the torso that would be visible from a different perspective.
3. Sometimes the cues are there, you know the strike is coming, so it was telegraphed BUT, action vs reaction being what they are, the strike was too quick to permit a proper reaction.
4. A combination of any of the above.
I'll use, as an example of a combination of number 2 and 1 a kick that exists in Hung Gar and Wing Chun. It sometimes gets called, romantically, the shadowless kick. What makes the kick appear untelegraphed involves a few things but the biggies are speed and distraction. I had a Hung Gar guy tell me that basically you use a distraction from the hands, a grapple, feint etc., that causes the opponent to look up and then you kick low, which contributes to how quickly it hits after launch.
WC is similar. You distract. Maybe a bil sau towards the eyes, a tempo or facing change that appears to be a set up for a different attack etc swapping to your strong side being the Wu hand often makes people think a punch is inc in my experience, especially if followed by a feint... then you kick, often simultaneously with the feint.
In either case if you were looking for the kick you would have seen it coming, a change in knee or foot orientation etc, but the distraction either completely masked it or, due to the speed of the kick, the distraction delayed your realization that the kick was coming to the point you couldn't react in time. In the end though the signs were still there, you were just tricked so you missed em.