This answer provides some highlight into this topic, but it is related only to Massachusetts (USA) PEs. For any other state or country, look up the rules. But it follows this:
The MA PE board posted that the one of the Basis for Discipline is:
(1) The Board may initiate disciplinary action against a Registrant or
an unlicensed individual or entity on its own or upon written
complaint of any individual who alleges violation of any law or
regulation within the Board's jurisdiction, including but not limited
to M.G.L. c. 112, §§ 61 through 65E, 81D through 81T and 250 CMR.
(2) The Board may, after a consent agreement between the parties or an
opportunity for adjudicatory proceedings conducted pursuant to M.G.L.
c. 30A, discipline a Registrant if it is determined that the
Registrant has engaged in, without limitation to, the following types
of conduct:
(a) misconduct or any crime involving moral turpitude; fraud; deceit;
incompetence; negligence; or exceeding the authorized scope of their
registration; [1]
MGL Chapter 112 Section 61 states that:
A board of registration under the supervision of the division of
professional licensure may discipline the holder of a license,
certificate, registration or authority issued pursuant to this chapter
or chapters 141 and 142 if it is determined, after a consent agreement
between the parties or after an opportunity for an adjudicatory
proceeding conducted pursuant to chapter 30A, that such holder has:
(1) engaged in conduct which places into question the holder’s
competence to practice the profession including, but not limited to,
gross misconduct; practicing the profession fraudulently; practicing
his profession beyond the authorized scope of his license,
certificate, registration or authority; practicing the profession with
gross incompetence; or practicing the profession with negligence on 1
or more than 1 occasion;
That being said, the PE can be held liable for any thing they recommend, espiclially if it is well documented, and it clearly states that their recommendation is really wrong. For the above example, where the SE user asked about cracks in the wall - I would sound an opinion, but would suggest to go and seek an in-person inspection. Especially that later on on MGL 126/61 it is stated that the board commite is not limited:
Nothing in this section shall be deemed a limitation on a board’s
authority to impose such reasonable sanctions as it deems appropriate
by the board after a hearing or by a consent agreement. A person
sanctioned under this section shall be subject to such other sanctions
or punishment provided by law. The boards shall promulgate such rules
and regulations not inconsistent with chapter 30A as necessary for the
filing of charges and the conduct of proceedings.
Lastly, if you are an engineer, be responsbile for what you claim, some stuff can hurt, others can kill. Be careful in what you recommend and in what you offer. I am not a lawyer, but am an engineer. I wouldn't recommend that guy to live in that house anyhow, because to me it looks unsafe. But hey, it is only my opinion, and take on it...