It's about how quick and sharp the initial move is and how forcefully it gets faded.
Look at your shoe - if you pulled the laces apart really hard, the shoe would recoil temporarily, but it would be looser until it was tied up again - same thing with the market - if there is a very forceful move - the temporary retracement is often a chance to get involved in the direction of the trend (the sharp move) - just watch how it reacts during the retracement to a significant level.
On the flip side, when a market is slowly moving without any sharpness for a fade to take place, then that's just as good.
As always, it's all about risk/reward. Mark your spot - hopefully one of relevance - and get in (and out if it moves against you).