No crime in using hooks not designated "fly hooks". Offset hooks usually don't have a good action in the water, so avoid them. Also, cheap hooks often don't have sharp points - and sharp points are key to getting good hook sets. Cheap hooks that don't perform are no bargain.
For bass bugs etc it's OK to play around with what hooks you can find locally. Problem is, the better bass hooks with the super sharp hooks are most often expensive, but if you find them in the bargain bin go for it.
Saltwater hooks should be stainless since they will rust when put back in your fly box if they are steel. However, if they are simple flies that get chewed up and wouldn't be put back in the fly box, plain steel is OK. The rinsing thing only goes so far. The hook will rust deep inside the fly after being wet, so a rinsed fly with a steel hook can look fine, but break on a good fish since it is shot inside.
I'm of the fly tying school where one tries to be creative and find cheap materials at places other than a fly shop. Of course, the materials at a fly shop are usually better suited for fly tying - but that doesn't stop me from trying other stuff.