I  love making out and lately some dudes breath is out of the ballpark gross. I can only assume that there is little to zero oral hygiene involved.  Possibly some wild donkey ass licking?  I don't know how else to explain the shit breath. I mean this in the literal sense.  They approach at the door.  I move in for a smooch and there it is, bunga breath.  I stock toothbrushes,  floss and mouthwash. I welcome everyone to use whatever they want. Some do and after a bit the caca odor resurfaces.  At times it has caused my eyes to water and in one severe case I actually gagged HARD. 🤢 Whiskey  Tango Foxtrot   I had to abort and play sick. The gag made that really simple. No refund stinky!  
So fellas do you want to know right off the rip if your breath is a force to be reckoned with?  There really is no pleasant way to say it. I thought my hint was good enough and it wasn't.  It's like asking if a fella would like to take a shower.  No they don't they want to fuck you. So, now showers are mando because I like fresh nuts. Fresh nuts and fresh breath are key imo.  If I had bad  breath and poo poo pussy how would you tell me. Let's reverse this. 👍

Both breath and pussy smell arise from bacteria. Both can be affected by what we've eaten.  

So of course I am obsessive about it.  Brushing teeth, mouthwash, mints, etc.  I do not mind being told about it.  It bothers me and I don't really know the cause, other than age and maybe some gastrointestinal problems.  The key is to have people in your life who are honest with you, and to be on top of it.  I'm sorry.

I'll bet most of the guys here know about oral (and other) hygiene.  The guys who don't prepare their mouths for DFK are also probably the ones who leave skid marks on the sheets.  The only thing to do is to not DFK them at the door, escort them to the bathroom and have them use mouthwash and rinse their junk and ass in the shower.  Just be nice about it.
Bad breath is caused not only by bacteria but by decaying skin from all the surfaces of your mouth. The best way to deal with bad breath is to do the following:
1) use a tongue scraper.
2) brush not only your teeth but your gums, the inside of your cheeks, the roof of your mouth and your tongue.
3) gargle with an oxygenated, non-alcohol rinse.
4) floss.
Still not a real dentist.

You girls put up with a lot sometimes I don't know how you do it. But I have heard of stories of guys doing this on purpose also. That said I like to smell  clean and fresh chew gum than breath mints before I come in. I had a provider that turned me on to a new deodorant that has helped because I am very active. If a girl likes a certain cologne I would wear it. And if I did not smell perfect I would like to know.

I am very sensitive to my own ability to not smell the freshest at times. So, I try to do the 3 S's and brush teeth plus non alcohol mouthwash within an hour of the session.  Before I enter, I use breath freshener again. It is part of getting older.
I happily take a shower upon arrival, I like the sensitivity of being freshly washed and a mouth on my cock.

"Decaying skin" is decaying because it is being eaten by bacteria.   It is good to scrape away that bacterial food source,  but the stink comes from the bacteria.

What kind of cologne?

for people with halitosis.  Anything that dries out the mouth will cause it to return.  Mouthwashes good for dry mouth are Biotene moisturizing rinse.  Many medications will give people dry mouth.  Keep a bottle of water to drink nearby to keep mouth hydrated.

I take pride in taking good care of myself. No one is going to do it for you. And people need to know that the older they  get the harder they have to work .A good overall health  prolong life,health , and happiness.  

or even better is Therabreath.

Therabreath contains a couple chemicals that achieve oxidation -- similar to bleach.  You could say bleach is the poor man's Therabreath.

Hoping this helps

Flossing is essential. That burrito you are gets lodged between your choppers and rots. LITERALLY  Most importantly,  nothing trumps a trip to the dentist. That person will be honest.

Insurance might be an issue for some folks---but if you have dental insurance there's absolutely no excuse for not getting your teeth cleaned professionally at least once a year!! (Preferably twice a year.)  Plaque and tarter build-up are huge contributors to foul breath!!

totally waiting for someone to be like "but you said rinse with bleach" followed by a sad story about the hospital....

if the gums every bleed with flossing it is past time to get tarter removed professionally.  All the oral hygiene in the world can not take away the tarter behind the lower teeth in the front.  

All the symptoms described by the OP suggest gum disease. This happened to me years ago. I had a very forgiving ATF at the time and it took another person to clue me in. Once I went to an orthodontic surgeon to have the diseased tissue removed and repaired and everything was fine. Major lessons: this is a painless disease, until teeth fall out or excess bleeding of the gums occurs you won't know you have it; most dentists actually do a terrible job of cleaning teeth; most people probably have never been properly instructed in oral dental care - for example do you know what an interdental appliance us? It is something you should use every day.

If you have good dental hygiene (brush your teeth and floss, etc.) yet you still can't get rid of this toxic breath that seems to be coming from your throat and back of mouth area, it is most certainly tonsil stones (tonsilloliths). If you never heard of it, google it. It's a real thing and a LOT of people have it, both men and women. Most people who have it don't know they have it and just live with it.

That is what I use, no complaints yet. I also use their toothpaste.

... in my opinion it's really in a whole different league than alcohol based mouthwashes that taste too strong at first and don't really resolve the problem in the long run.

You know how when you try and smell your own breath but you can't, well I believe if you kiss/ lick your own hand, then smell it, if you have bad breath your hand will smell funny.

You are absolutely correct.I credit my very strict mother everyday. Could not drink nor smoke,not even when I was away at school.So glad I never started.
Hope the people who believe they are addicted find the strenght to quit.

I use TheraBreath toothpaste, mouthwash, tongue scraper and always pop one of their breath mints in the elevator on the way to her sex den.
Plus, my ass is clean.  Cuz I use TheraBreath Ass Suppositories. LMAO.

My dad was a smoker.  He was pushing up daisies by the time I was in seventh grade.  Kind of took the fun out of the idea.

First of all, a guy should see a periodontist to be certain he does not have gum disease.

Yes.

to gargle with undiluted bleach after reading this.

Even highly diluted bleach water scares me off ... I use hydrogen peroxide, either full-strength or half-and-half with water. Same general principle as the bleach, I think.