As others have said it all depends on the office. What do people wear the rest of the time?
Many offices are not professional dress wearing offices, regardless of the time of year. In many, women are wearing t-shirt type tops, casual skirts or trousers or even leggings or jeans, plus they might be revealing cleavage or a lot of leg in some offices. If this is the office norm, then a spaghetti strap and bra strap on display would seem fairly normal, along with sandals or even flip flops. Office definitely doesn't equal smart. Many blue collar jobs will have smarter employees, often in a uniform.
If however, your office has men in shirt and tie and women in tailored dresses, tailored skirts or trousers, then to suddenly don a spaghetti strap would be a bit odd - rather like the men suddenly appearing in shorts. Most offices might become a little more informal in the hot weather - so dresses might be sleeveless - but still tailored and with wide shoulders, and the workers probably cover their shoulders for clients. Short sleeve tops would be pretty normal. In lots of offices, bare legs wouldn't be the thing and women continue with tights through the summer and sandals certainly wouldn't be considered workwear.
There is a huge variety.
However, I tend to think that anything which reveals loads of flesh is best kept for weekends and holidays rather than the workplace.