The problem with that idea of real risks is that it sounds like theres a final answer out there, which there isnt. What your risks are depend on so many factors, not least of which is do either you or your partner currently have an STD (which is information you may not have before having sex).
Some people say that if youre having casual sex you should act as if everyone youre sleeping with has an STD. This isnt meant to be scary, or to suggest that you should necessarily avoid having casual sex, instead the idea is that if you treat everyone as if they have an STD you wont have to constantly worry if they do or they dont and change your behavior from one situation to the next. This also seems like a good time to remind you that there is basically no kind of hot, raunchy, wild sex that you cant make safer by using condoms or other barriers.
Its hard for researchers to determine how risky oral sex is, since most people who engage in oral sex also engage in other sexual behaviors, making it impossible to know the way that an STD was transmitted.
That said, there are a variety of STDs that can be transmitted during oral sex (including herpes and HPV) and its probably worth learning more about the STD risks of oral sex so you can decide what level of protection youre going to use. assessing your risk and then making informed choices about the risks you are willing to take.
Read more Is oral sex safe sex?