I have been studying the double bass for about 3 semesters now.
At first I used to look at my left hand all the time, but now I find that I am improving enough in my intonation that I can read the music and still maintain a good sense of intonation without having to visually guide my fingers as much. At least, for the first several positions....After that octave G and A on the G string, it gets a lil hairy, heh.
I still take a glance here and there to gauge my bearings after large leaps in notes/positions...Im definitely not perfect by any means, but with more time and practice, you can get away from looking at the fingerboard. What I have tried to do is get my ear more involved. If your not sure about a pitch, compare it to an open string or something concrete...Like a tuner

I would recommend buying a pitch tuner, that way you could help tune your ear by setting the pitch and running up and down scales to hear how it all sounds in relation to tonic....Just an idea.
As for markers....I actually never had 'em myself, though When I was starting they would have helped so much....However, I find for me personally, I think I learn better/faster by being "thrown in the deep end" so to speak.
I wouldnt think theres anything morally wrong by using them, and I dont think it means that one is an inferior bass player....Heck, if it helps you play well, take advantage of it! I guarantee that after awhile, most people will become so comfortable with the instrument that they will find themselves using them less and less.