Is there typically a poly for secret clearance?
Qazw is correct. The position either requires that level of clearance/poly or it does not. I have Secret, TS and TS/Poly working at my site. As people demonstrate skill, competence and desire to move up, I encourage the TS/Poly. You can receive a directed or Criminal Poly under special investigation…but likely not.
I wanted to add that a polygraph (reliable one) is actually useful in some circumstances for instance: when your human resource personnel does not remember you or confuses you with a bad employee and gives a negative reference and you have no other recourse (assuming you find out) to sue or to just use the polygraph results and responses to prove that no such event did occur and they did in fact confuse you with some other person.
Mistakes like this rarely happen as most people who prefer to give the response: “we do not recall this tenant” if they are faced with government personnel or contractor from an agency with powers of arrest or they have something to hide themselves or if they are just lazy or in a bad mood that day. That is almost every agency that the US government has under its jurisdiction from the USPS to the Veterans Affairs to the USDA and US Forest Service.
It doesn’t matter if any of us as individuals feels a Poly is valid or not. Only if your agency requires one and if they find it valid.