Watering plants with milk is not a good idea because it seems to prevent the plant from sprouting. There is fat, protein and some sugar in milk which can be a food source for bacteria. Bacteria spreads quickly and may hurt the plant as it starts to grow (that may be why it smelled worse than the other plants). Even though calcium is good for plants, it would be better to use crushed eggshell compost or soil fortified with calcium since roots take in minerals from the soil.
Milk is good for growing humans but not for plants!!
Bibliography
DK Children's Illustrated Encyclopedia, DK Publishing Inc.