No, I don’t feel offended. I usually try to tell myself that they may not know better. I also think that modesty is becoming something that is in the mind of the beholder. I would prefer that the Church establish a broad expectation, ie, for women, shoulder’s covered, neckline no further than two inches below the clavicle, no shorts for anyone, no armpit hair showing for men (tank tops), etc. I don’t care if people wear jeans to Mass, I’ve lived in rural areas where nice jeans were anticipated as dress wear. I don’t think it does, for us as lay Catholics, to become the “clothes police.” We don’t know the circumstances people find themselves in, what they can afford, etc. The emphasis should be on modesty and keeping things covered that should be covered.
Also, I live in the Mojave Desert. We regualarly have one or two, usually elderly, people faint from the heat in the summer at Mass. People should dress in a way that is adapted to their physical environment, but observes the standards of modesty (example: our bishop and priests should be permitted to wear white cassocks, soutanes, and clericals in the summer time, as they are permitted in India and other hot weather tropics).