Good Secret Shopping Company for Student-Housing?

Over the past couple of years, I've grown dissatisfied with the quality of mystery shops that I've seen at our student-housing properties. The shoppers always use a very similar story ("I'm actually looking for my son/daughter..."), and my on-site staff members can almost always identify when they were shopped. They even will email after a secret shopper has visited the property to tell me they were shopped, and they're very often correct!

My frustration is that when staff members are aware that they are being shopped, we will not get an accurate representation of their performance. At that point, what could be an extremely valuable tool, from a training and performance improvement standpoint, becomes less useful or even useless.

Does anyone know of any companies who perform mystery shops in the Southeast that use younger shoppers and perform great shops? I want to continue this practice, but not if we are no longer getting valuable information to help our properties improve.

I don't use shopping companies. I've actually hired individuals (in the case of student housing, go with someone 18-22 years old) and had them report back. I have them document everything, from the inquiry sent online to the phone call, visit and all follow up. I have had great success, and it costs me far less money.

I have my own report form that I use, and well as requiring copies of all written/emailed communication, community marketing materials (brochures, application, business card). The form must be filled out completely to receive pay. We pay our shoppers as independent contractors.