I have never done that....all sugar water is going to do is give them a sugar rush (like it would a child).
Pasty bottom is to be cleaned off ASAP....if it does not come of easy, then take a warm wash rage and hold it on the chicks bottom until it becomes loose and then pull off the poop. Sometimes the down will have to be trimmed around the Vent area (if you do so be VERY careful not to cut them ).
If the chick acts sleep or weak, then give them save-a-chick or use vitamin or electrolytes in their water.....
Also feel tier bottom to make sure they are not Impacted with poop.....feel for a hard knot in the bottom vent area...if impacted...soak their belly and vent area in a warm bath (then make sure to blow dry them on low setting until dry. a small amount of oil can me put on a q-tip then applied to outside and slightly inside the vent area.