I *might* bathe my dogs twice a year. Might. The exception to that is a rinse if they get "snowballs" in their furnishings, or if they come back from a particularly sandy beach trip - but I don't generally use shampoo for that.
Unless you have a dog who gets truly *dirty* in mud, dead things, etc (which in that case, bathing is necessary!), in the rest of cases coat health truly comes down to mostly diet, partly genetics, and other coat health (brushing, combing, furminating, etc). My dogs are rarely bathed, but they always have shiny, healthy, clean-looking coats, no flaky skin, and never feel greasy or dirty.
Zipper has a seasonal allergy, which also causes a flare-up of Schnauzer bumps (Schnauzer Comedome Syndrome) from time to time. We do control it mainly through diet, and flare-ups are now rare, but when they happen he does need a week-long round of spot-shampooing down the center of his back (where these clogged follicles occur). But it's a special soapless shampoo that is designed to be used only in that area - the rest of his body is unshampooed.
So no, you aren't a bad dog mom. :-) And it's well known that in some cases - too much shampooing is very UN-healthy, and will cause greasy, oily, dull coats because you are constantly removing the natural oils from the coat and skin.
"Zipper" Ykelenstam's Zippity Doo Da, CGN
"Gaci" Ykelenstam's Moxie's Legaci
"Shimmer" Ykelenstam's Shimmer 'N Shine, CGN RA
"Kash" - Ykelenstam's Pay It Forward, RN