Shop recommendation

What is your question?

I recently had the oil changed in my Honda Accord, and the (Goodyear) Gemini shop serviceperson recommended that I add an engine cleaner called BG Quck Clean & BG MOA because it looked like there was some "muck" building up. He also showed me the interior air filter and wanted to know if I wanted them to change it. Does a Honda Accord need an engine cleaning additive? How often should one change the interior air filter?