Chances are the black specks are a sign of fleas. You can usually tell if they have them, yoou can look at places on their head and on their stomach. Also, they will have scabbed areas from scratching. I noticed on my maine coone, Samantha, that she had scabbed areas at the base of her back, right in front of her tail.
I recommend the Revolution, yes, its a bit more expensive, but it works wonders! My calico, Little Miss, had ear mites, and the vet gave me the revolution, and it got rid them. It isnt anymore difficult to apply then the frontline or advantage.
The other thing that you should watch out for, is that if your cats eat a flea egg, they can get intestinal worms, and have to be treated for that as well. Thats why flea control is important. I learned that hard way! Little Miss was a rescue and after a day or so of having her, I started noticing these hard pellets that looked like yellow pieces of rice...thats what worms look like, but there weren't any in the litter box...none on her. I finally scooped some up and put them in a bag and took them and her to the vet. She had tapeworms! This is something that outdoor cats tend to get, but it's a good piece of information to know! Luckily, the other didnt get them.
I hope I helped you some.