It all depends on the relationship dynamic between the individuals involved.

For me its not as much about the what so much as the how; some acts are inherently viewed through out history as being less dominant that others.

There is a big difference between someone taking on a submissive posture with their ass up and face down while begging for an ass fucking and oh say strapping their submissive down getting them hard and then posting on top of their cock and staying in complete control.

With some people once the dominance is relinquished its twice as hard to regain.