Many won't go to church if all they have is a ratty old pair of jeans. Because of the social construct it makes them feel bad, less than, others. Others that can't deal with those who are less priviledged. Nobody wants to go somewhere that makes them feel bad.
Example; I used to fellowship with a group called the "I found it" movement, hippys, stoners and surfers who put down our bongs and picked bibles. I was outside with a couple of friends after service, with my bible in hand. Some lady walked up and asked if I knew Jesus? My friends started quietly chuckling. Yes I do I responded, why do you ask? Well you don't look like you do. She replied. My buds broke out laughing.. She got offended. It's like she thought there was some kind of secret dress code or uniform Christians should follow to come worship the lord. Wow, culture shock