In my opinion (which definitely could be wrong), sheiks dash dance is bad and not really useable in the same way as that of marth/fox/falcon. With their long dash dance those characters can simultaneously put pressure on an opponent and remain relatively safe from counterattacks. Long dash dances are good mind games because it makes it difficult for your opponent to know exactly where you are, or exactly where you are going to be. With sheik, however, dash dancing can only cover a small area, and isn't much different than standing still. I always feel that by dash dancing I limit my defensive options (can't ftilt easily), and also that I don't confuse or intimidate my opponent much because the dash dance is so short. Most characters can hit sheik out of her dash dance easily with something like running nair.
Therefore I believe dash dancing, at least the way it is used by marth/fox/falcon, is useless or even harmful to sheik's neutral game. However, it definitely still has its applications. Using a single dash dance to evade an attack and grab/dash attack your opponent is definitely super good. Dashes can also be a great movement tool when combined with wavedashes. The wavedash, while slower and laggier than dashing, allows sheik to cover the extra ground that her dash dance cannot.
Dash dancing is also not a bad option when applying pressure to an opponent. If you have someone on the ground or in shield, dash dancing close to them can be a reliable way to bait out a spot dodge, roll, getup attack, or any other laggy and punishable option. It also has its uses in sheik's combo game.
I think incorporating pivots into sheiks dash dance has the potential to make it way more effective. Used defensively, a good dash dance could bait out an approach from your opponent. Without pivoting, you wouldn't have access to your main tools for stuffing an approach. However, dash back -> pivot f-tilt could be incredibly powerful if applied correctly. Depending on the situation, you could also pivot any tilt, a jab, or down smash. I feel like pivots could have the potential to make sheik's dash dance viable in the neutral game against most characters.