Is a pap smear a good tool for general cancer detection or is it only specific to cervical cancer?

Specific: Pap smear is a screening tool for cervical cancer.

Usually, yes: A cervical cytology (pap smear) is scraped along the cervix usually, but can also be scraped along the vaginal wall. Squamous lesions (dysplasia or carcinoma) are the most commonly found. However, endometrial tumors are shed through the cervix into the vagina. Certain sarcomas (rhabdomyosarcoma: malignant skeletal muscle tumor) can also be found. Generally, a pap is an excellent screening tool.