Both cats are sniffly, why?

Just adopted a new cat about a week ago and shortly after he arrived he started becoming sorta sniffly and acting like he had a hairball to get rid of (totally plausible, he's a very floofy Maine Coon!). Our original cat (a short haired Tabby cat) came to us from a foster who worked through a cat rescue and was sick herself when she came to us with what we were told was a kind of "cold" and she had medicine for it. Once she was done the medicine she was better for 2 weeks or so then seemed sick again, sneezing having a very stuffy nose, weepy eyes occasionally etc. Took her to the vet and they thought she had developed a secondary infection while trying to fight off the cold, gave us antibiotics. She used all them and she got sniffly again a few weeks after. She has a great appetite, her lungs are clear, boundless energy just sneezes often, has sometimes greenish/yellow mucus from her nose that she sneezes out and rarely her eyes develop crusties. When we took our other cat to his first vet visit with us today and asked abut the sneezing/hacking they said his lungs are clear, eyes are bright and clear too but took blood just in case. Any idea what might be plaguing my little fur babies? We've been bouncing ideas off each other from allergies, kennel cough, and even a strain of the herpes virus (vet told us it could be this but pretty much there's nothing they can do unless the cat develops issues seeing and then we'd add lysine to the food but she didn't think it was it, but gave us no real answer). I'm more than a little frustrated that our vet doesn't seem to know what's going on with our cats and that this excessive sneezing, breathing difficulty, and mucus seem to be common among normal healthy cats to her! We go to Petco's vet service Banfield I think it is since they offer insurance plans and at the time we didn't think that we'd need to see a vet often. I just hate to see my cats look miserable and be woken by their own sneezing not to mention I'm not overly fond of being sneezed on all the time (just this morning I was awoken by my female cat sneezing all over my face and on my pillow, complete with a big greenish/yellow glob of snot resting on my pillow as way of greeting my day). Please help!

Did your vet take a culture?

My cat has herpes, and gives him crusty eyes. He never sneezes out boogers and if my vet refused to treat for that symptom, they'd need new wallpaper.

If your cats seen ok otherwise and the vet won't culture your cats, you might try lactoferrin. Bovine lactoferrin. I'm about to try it--it's supposed to help with feline herpes virus.

Isn't Banfield through Petsmart? Just curious, because it is by me. Petco has Vetco (so original, lol).

Anyway, I also would say if you feel like you can't get anywhere with your vet, then go for a second opinion. Unfortunately it will probably be a bit more costly since your insurance most likely isn't any good outside of Banfield (I was looking at pet insurance the other day and saw it, but I don't go there so couldn't use it).

My Lucky had those symptoms and he had to take an antibiotic also for it (and for the life of me I can't remember what it was - Clavamox maybe?). He had what was more like a sinus infection than a cold, poor little guy. And instead of having snot, he was all stuffed up and getting something akin to post-nasal drip, which was making him cough. And he was good after the antibiotic.

Update: we took our original cat Tabby back to the vet since she has been off and on sneezy, mucus in her nose, unable to breathe through her nose etc. They did blood work on her this time and it turns out she has Feline Leukemia. When we were there last with our new boy Tiberius, his blood had only shown slightly elevated levels of white blood cells but we're worried he might already be infected as well. If there's anyone out there who has Feline Leukemia cats, please if you have any advice etc. It would be greatly appreciated. We're all devastated and we heard that most cats only have about 2-3 years before they succumb to lymphomas etc.