Well Mr. laid_back_alex,
I agree that no girl or agency should text the client if he didn't give them permission. It should be a no brainer. Frankly, in my years of hobbying, very few girls have texted me without ever giving them the green light to text me after meeting them for the first time. It didn't bother me when they did because I was free to text them back or ignore, depending on my experience and if I wanted to repeat with them. I'm not worried about the S.O. finding out as I am not with her and completely single.
So, having said that, the circumstance is very different when it comes to a married men or a guy in a serious relationship. Let me rephrase again, are you insane to give them your personal and work number if you are that committed to a relationship?! You said yourself that one unsolicited text could ruin everything! So the best possible precaution is to be very discrete in sharing a number. Even if you had faith in the agency or trusted a girl to not send you a text, who's to say an accidental text would never happen? Or maybe you had a falling out with the girls/agencies and they revenge text you?! Anything is possible, right? So a burner and a text app may not be the most discrete, but it sure as fuck is allot better then your personal number! You can always discard your burner or log out of your text app... All I'm saying is that if you value privacy and discretion, a proper precaution is needed!