In my opinion, the faithful may dissent from the ordinary teachings of the Magisterium, without incuring guilt, under certain conditions.
The most common case of faithful dissent occurs when an individual Bishop teaches in a way that contradicts or undermines the teaching of the body of Bishops, or of the Pope, or even of certain infallible teachings of the Magisterium. In such a case the faithful can, and generally do, regard that Bishop's teachings with caution and adhere instead to the opposing teachings taught by higher authority in the Magisterium.
The faithful are not required to believe an ordinary teaching of the Magisterium if there exists a contrary teaching with greater authority from the Magisterium.
And in general, the faithful can dissent from any ordinary teachings of the Magisterium on the basis of a more authoritative source, such as an infallible magisterial teaching, or Tradition, or Scripture.