How do i know if my doctor is trustworthy when he recommends hernia surgery? second opinion?

Ask: Go and see another surgeon. Most physicians are trained in their specialties and very knowledgable. You need to trust your physician. If you don't, look for another doctor.

If you ask he is not: Trust is between a doctor and patient. If you feel uncomfortable get a second opinion. A board certified surgeon with reputation should be able to handle a hernia. You might ask how many hernias he has done in the last 12 months. If less than 30'you might want a more experienced surgeon.