Personal Comment: I am not a lawyer and this is not to be considered legal advice.
The rights of anyone accused of a crime in Texas are as follows:
Art. 1.05.   RIGHTS OF ACCUSED. In all criminal
prosecutions the accused shall have a speedy public trial by an
impartial jury. He shall have the right to demand the nature and
cause of the accusation against him, and to have a copy thereof. He
shall not be compelled to give evidence against himself. He shall
have the right of being heard by himself, or counsel, or both;
shall be confronted with the witnesses against him, and shall have
compulsory process for obtaining witnesses in his favor. No person
shall be held to answer for a felony unless on indictment of a grand
Acts 1965, 59th Leg., vol. 2, p. 317, ch. 722, eff. Jan. 1, 1966.
as found here: http://law.onecle.com/texas/criminal-procedure/1.05.00.html
I was not able to find any rights specifically for prostitution.
Here is the penal code chapter on prostitution in Texas
According to this site: http://statelaws.findlaw.com/texas-law/texas-prostitution-laws.html
Some defenses to a prostitution charge can be:
Entrapment (i.e. by an undercover police officer)
Duress (i.e. the defendant was under threats of bodily harm if they did not commit the sexual contact for a fee)
No money was received for the sexual contact
Lack of knowledge
That last link has a good overview of the Texas prostitution laws.
I hope this helps!