First impressions are often the most lasting, and lets face it, we are a visual animal. How you look affects how people percieve you. If I'm going to a bank, and i am approached by an employee that is dressed sloppily, the first thing I'm thinking, is "if this fella can't even tuck in his shirt, and look professional, how is he gonna manage my money?" I don't care if it is a t-shirt, a hawaiian shirt , or a suit and tie. I feel that whatever business you are in, you need to look like you are ready for business. If it is lawn maintainance, then jeans and a t-shirt are it, but a doctor, or a lawyer should dress to reflect their professionalism. To a certain degree, the clothes do make the man. For example, I would have a hard time with one of my children's teachers being in front of the classroom everyday dressed like a hooker.
How you look can also affect how you behave. Example from my life : as a stay at home mom, I don't even have to get out of my jammies, unless I am leaving the house. I have also struggled with being a horrible housekeeper. A couple of years ago, a friend gave me some advice. Get dressed every day, all the way down to tie-on shoes. Look like you have something to do, and your mindset will catch on. I am a betetr housekeeper than I used to be, but I find that on the few days I lolligag and pad around the house barefoot, in my nightshirt, I have no motivation to do much. When I get up, get dressed, all the way to my tennis shoes, and make the bed, I'm ready to tackle a day of cooking, cleaning and child care.
As for, church, as my pastor would tell you, that if you can, come to church clean and dressed modestly, but if you can't, then coming as you are is better than not coming at all.