This is why I don't use booleans very often: all the cleaning up to get an all-quad-model (which I probably would do in such a case). But there are no rules in poly-modeling (no subdiv), and for subdiv-modeling it's more guidelines than a rule you have to follow.
Even while I advocate all-quad-modeling, there are a few exceptions (very view) where you end up with a tri you can't get rid off or (even more seldom) with a ngon that looks perfectly well but as soon as you cut it up, you'd have to remodel half the mesh because of serious pinching or so (in such situations, though, I sometimes go back to an early version of the model to do the whole stuff anew, this time trying to avoid the ngon-situation. With tris I usually can live).