Though it's fun and I love doing it

Should an escort prepare for cross-dressing if it's in listed services or they don't even bother

Of course she needs to prepare, You also need to tell her your desires. If she loves what she is doing, she will prepare, and you should leave a generous tip for all that 

Yeah she needs to prepare. Every service the escorts offer needs preparation. It isn't just meeting, sex and collecting money for them, it's a job.

Escorts always prepare like everything from their appearance to places and to things they use during the meeting. 

Of course they do, you can also bring the outfit that you want them to wear if you want a specific look

Yeah cause why would she list it in her services if she's not prepared for it?