What alcohol concentration makes bathroom cleaner "disinfecting"?
According to this Center for Disease Control document:  


  Ethyl alcohol (70%) is a powerful broad-spectrum germicide and is considered generally superior to isopropyl alcohol. Alcohol is often used to disinfect small surfaces (e.g. rubber stoppers of multiple-dosemedication vials, and thermometers) and occasionally external surfaces of equipment (e.g. stethoscopes and ventilators).  


Although 70% alcohol is ideal, another CDC article states that it can be effective at 50%.  According to this article:  


  In the healthcare setting, "alcohol" refers to two water-soluble chemical compounds—ethyl alcohol and isopropyl alcohol—that have generally underrated germicidal characteristics.  FDA has not cleared any liquid chemical sterilant or high-level disinfectant with alcohol as the main active ingredient. These alcohols are rapidly bactericidal rather than bacteriostatic against vegetative forms of bacteria; they also are tuberculocidal, fungicidal, and virucidal but do not destroy bacterial spores. Their cidal activity drops sharply when diluted below 50% concentration, and the optimum bactericidal concentration is 60%–90% solutions in water (volume/volume).  


So, alcohol has certainly been shown to be a powerful, broad-spectrum antimicrobial agent, though not at the dillution you proposed. I would just use the straight vodka if it were greater than 50% alcohol, or probably beter (cheaper) yet would be denatured alcohol if that's available where you live.