To UJM and friends:
Are you too indolent to read the previous posts? All of this and more have been covered and explained already.
Do yourself a favor, learn Mishna B’rura with a posek or rav and you will eventually get to know how to analyze and interpret the Mishna B’rura on your own. It’s hazardous to just read the words and paskin on your own.
By the way, do think a Rav would allow someone to daven without a hat or jacket in his shul if that person was being oiver an aveira by doing so?
Also, to clear the air, I do daven with a hat, and jacket, and tie, and take off my boots, and do not daven with a coat on, and trim my nails every erev shabbos. But far be it for me to think that I or my t’filos are any better than someone who doesn’t.