It's not necessarily hygiene.  Some women just have bacterial issues.  They recently found that even anti-bacterial hand sanitizers only set the bacteria back about 20 minutes.  

Honesty....

I'd rather someone to nicely tell me then to not. Fortunately,  I haven't had this happen but if it did, I might be a little embarrassed but I would go to the Dr.  I'm surprised that this has come up on several boards lately and that women don't check their vaginas themselves before seeing someone.
XOXO  
TL

oftentimes a lady's "unpleasant odor" is caused by a pH imbalance.  And lucky for girls - many many things can throw off the pH of the vagina such as her period, sex, diet, douches, soaps, etc.  When the pH is off it is likely to result in a very fishy foul smell that sometimes goes unnoticed until she's having sex.  Fortunately, there are over the counter products that instantly correct the issue.  There is a good thread on this topic on TOB.  

xoxo

I made the commitment to see a pornstar for a rather expensive session! I was really excited for the meeting! I arrive and things get going really well. Then my date suggests some 69, so I take the position! Almost immediately I realize that her bung hole smells like... well a bung hole!  I almost immediately lose my erection , not to be recovered in that 60 minute session!  That was kind of embarrassing! Should I go back and ask for a RE-do? In hind sight l, it was worth a laugh, but also frustrating!

with the providers you wish to see again.  You can do it through email if it seems embarrassing or disrespectful to you.

You said when you moved to doggie you smelled an odor.  I would tell the female what kind of odor you smelled to help her better address the problem.  I am guessing it is one of the two:

A- If a strong fishy smell then her PH is off in her vagina
B- If a feces smell she could had some leakage being pounded from behind

Both would be very embarrassing to me, but I would want to know if something is happening down or back there.  I would rather a guy say "I think we need to jump in the shower"  or "you might want to check yourself back there" than have an embarrassing review for the world to see.

Madison

Goes both ways. How do you know it wasn't you? They're supposed to be professional and honor the service. But if you show up all nasty as fuck, WTF? Just cuz you're paying doesn't mean you get a pass. Especially if you want a cool reference.  

Sometimes when I'd see a lady I'd say let's take a shower together. Mainly cuz sometimes I just got off work and didn't want to subject her to anything she might not appreciate and sometimes it was a form of foreplay.  

In any case, it was fun washing each other. Being comfortable for the anticipation of what was to come....

The best way would be to just be honest.  

Anything can throw off PH including food and medications.  

If it’s BV that’s easily spread from base of the dick so make sure you protect your full shaft.  
Most times it’s just not cleansed properly.
Some women even use harsh cleansers down there that make it worse.

It’s better that you let her know so she can go get her kitty checked!

How can a woman not notice a fishy odor??? OMG! I always smell my panties because I really like the way that I smell lol. I have started eating way better than I used to eliminating regular foods that I used to eat all of the time and yes I noticed that my pussy scent has changed. I don't douche with anything and no soap up in there. I did it once in my teens with the soap and got a painful yeast infection. My gyno flipped when I told her that I used to douche. Smells while intimate, damn that's tough! I did a three way with a lady that had peed but did not wash. I went to taste her and well, there was a pause and then a "ooh baby why don't you just fuck that sweet pussy!" I had to say that because I sure wasn't gonna put my mouth there after that smell rose up!  

I have often wondered what I can say to guys that have smells. Twice as a provider I stopped due to running into so many smelly guys. One guy smelled like he had just taken a fresh dump. Another one smelled like he grated cheese with his balls, the good cheese that smells bad lol! The one I have experienced more than anything is the bad breath. Smells like he gave Death a blow job. Just bad bad bad!!! So bad that I no longer see those guys anymore with the dragon breath. It takes my breath away and singes my eyebrows and it's just plain terrible. My client pools sadly has grown smaller. I am even afraid to see new guys because it seems many don't understand the concept of washing and brushing the tongue (For Pete's sake PLEASE brush your tongue!!!! After you brush your teeth, rinse off the brush and put toothpaste on it and brush. your. tongue. or use a tongue scraper) It's rough out there for us ladies too with hygiene smh.

I am definitely in favor of cleanliness. I don't wan't fecal smells or stains or strong BO, but I don't want a woman to be scentless and tasteless. I like the scent and taste of a woman's natural juices. A bit of armpit scent is okay too.  

For pros, the natural scents are much easier to clean off than perfumes, so I appreciate the your inclination to the absence of perfume.

I have had a guy that asked that I not taste like soap again lol. He wanted me when I was done running around doing errands or whenever. He said don't bathe! I want to taste you natural. I told him that I cannot do that. I am so obsessed about smelling clean that I would be on edge every time he touched me thinking OMG I smell like sweaty vag or something. I couldn't relax so I declined the date. That's way outside my comfort level. There are a few regulars I see for kissing only lol. Even with them I gotta bath although I know we won't go beyond kissing.