The male will lick the pee of a female, checking for all of what Carmen said. Who is here? How old? Healthy? Near breeding time? And usually he will lift his leg on or near the spot to leave his message to any other male callers: "Big, strong Cassanova has already chosen this bitch, so clear out!"
A neutered dog may or may not be driven to examine urine -- the uterine horns and bladder share some plumbing so one can tell more than just a little about a bitch in question. It probably depends on how strong his drive to pro-create was prior to the neuter, and how strong his instincts are; but that is just a guess.
A dog can gather more information from the urine than just how close a bitch is to estrus. So a dog that is interested, might be interested, but what happens after he lifts his head out of it. Is he dragging you along looking for the bitch in question, or is he just looking for the next object of interest -- I think that would depend on how ready the intact bitch was.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC