I agree with limonadinis, such geometry is no problem in many cases, this type of topology will indeed generate problems for animation deformations, but otherwise if it does not generate rendering/smoothing issues and is only for static uses then it's ok to use them.
Studio's with own rendering farms will avoid this type of models for technical reasons, but in most other cases it's not a problem.
For independent users/freelancers using off the shelf rendering software, this type of models can actually be a bargain because these type of models usually are inexpensive because they take far less time to make and they indeed render fine in most cases.
Also a triangulated mesh can still be subdivided if mesh density proves to be a problem or generate render issues, etc.
There is a market for this type of models so nothing wrong when the user is informed.
For some it can look unprofessional but that maybe more of a personal bias or preference of doing things.
Also see no problem to put it in a portfolio if you also have models that display your perfect topology ability's.
The models could for example display your fast sculpting ability's next to your other modeling ability's.