I feel sad for the OP as it is experiences such as she described that often jade a potentially good SP. However, with time comes ways to tactfully and 'professionally' deal with these issues. For hygiene issues, I recommend the following:
Bad breath: Tell the client that you recently ate something and would like to use some mouthwash first. Then poor 2 cups of mouthwash and offer one to him. When you are using it, they will not take it as a hint/insult and will likely appreciate the amenities you offer to them while wanting to use them so as to be fresh-breathed as well. Or offer them gum in the same manner....
Smell from bum/genitals: This one is fool-proof. During the massage, pretend to shake the bottle of lotion over your hand while 'accidently' squeezing a fair amount of lotion/oil on their dick. Then say 'oops, I better clean that up so it doesn't enter into you and possibly cause an infection or something....sorry'. Then get a warm wet towel and wash them thoroughly.
Body Odour: This one is all about positioning. Usually BO comes from unsanitary hair and underarms, so refrain from Mish with these guys and encourage standing bent-over doggy, or CG, reverse CG, etc. If it is a reoccurring issue, the next time you see them say "oh thank god you are here to visit me! I just had the smelliest guy in here who didn't shower very good for me. I'm glad you are here to give me a better time". He is guaranteed to shower his best after that is said prior to the session.
For monetary issues, have a tray with a note as earlier stated. It places the donation in plain view and can be dealt with after the session (so you know you are not being ripped off).
And all in all, a personal website works wonders too! We are in the age of electronics and internet research. Long gone are the drop ins only. Once people locate an SP via her website, there they can read about you, your etiquette, etc. and come better prepared. If you are just some random SP, you will get just random guys. If you are a classy business-minded woman, you will attract the same type of men.
And if all the above fails, simply become a DOM. A slave will rarely ever pull shit (typically out of fear), and if they do.....well, you can smack them and feel no guilt for it.