Yes, you can, and not only that, but I am of the opinion that it is the best way to judge exposure! Almost all I do to judge exposure is to look at the negs. I proof simply to see the images as positives, and to get a rough idea of the exposure and contrast, but I usually critically judge exposure by looking at the film.
Look at your mid tones. Do they look like mid tones? If so, then your exposure is good. Don't let high or low contrast fool you into thinking your exposure is bad. You can have a perfect exposure and have either a flat, a normal, or a contrasty negative, depending on many things. If you have all mid tones, your contrast is low. If you have few mid tones, your contrast is high. Contrast is mainly controlled by the light in which you shoot. It is also affected by the film, your exposure, and your development.
I am of the not-so-humble opinion that low-tone densities are not the be all and end all, and should not be used to judge exposure unless you are practicing tonal placement in a highly tested and controlled manner of working. The way I see it, high tone and low tone densities speak more to the luminance range in the composition and the development than they do to the exposure.