Unless you have bleeding gums and gengivitis, your chances of catching something isn`t even close to russian roulette (depending on what gun you use, that`s 1 out of 6). Herpes is sort`of obvious... so you can avoid catching it, you see weird marks around that area, don`t go near it. Obviously, if it doesn`t smell right, don`t force yourself either. You`re much more likely to get something from the she`s giving you than from giving her DATY. And even is close to nothing. If you`re afraid still, pick agencies and avoid Cr or Annon123; that`s already a good safer start; also you can always inquire about how often your SP gets tested when she`s over and you see her (PS. Try to do it in an ``en passant``... )
If I were you, I`d still get tested regularly, only of peace of spirit