I would say the most annoying line I ever here is anything around "No harm in asking", "Never know if you don't ask", "Hey had to try." any single line that tries to laugh off or excuse an attempt to negotiate. Some might do it, I don't judge any lady who does. But when you ask men. There is a harm, you are degrading that woman and telling her she is not worth the price she put on her own body.
Only clients you saw in the past should be allowed to message you in the evenings late.