Added for Katrina: You are lucky that your dryer vents weren't clogged. Clogged dryer vents don't just prevent your clothes from drying in a timely fashion. They also cause fires.
Your tech didn't know his job - he certainly didn't know how to fix a dryer. I'm glad your dryer is fixed now. Make sure to change your heater/AC filters every month - it costs you more money to run them with dirty filters, and puts stress on your system so that it can't work as efficiently.
Original:
How old is your house? How long have you lived there? Do you have pets? Did the people who owned the house before you have pets? When was it done last? Has it ever been done?
My house was 20 years old when I moved into it. The former owners had dogs. It had never been done before. I had terrible sinus problems when I moved in, was having surgery for it and didn't want to subject myself to anything that would complicate things.
I had mine cleaned. WOW! The stuff in there! I saw what the receptacle looked like before and after. So, it's not a scam if you have a reputable company do it.
It was kind of expensive (maybe it has to do with the size of your house, I don't know.) But since I don't have pets and haven't done "construction" on my house since, I won't be doing it again for a very long time. (If ever.)
So decide what your reasons for doing it are, looking at my series of questions.
Dawn