L’fi aniyas daati…
There is nothing INHERENTLY wrong with wearing (blue or black) jeans.
The question is, does your style of dress identify you with some particular group or hashkafah?
In some locales it does, in some locales it does not.
The same goes for colored shirts and many other articles of clothing that in SOME places are a reflection of a person’s frumkeit.
People must realize however the situation from BOTH sides.
By that I mean that those who feel that (no jeans) black pants, and white shirt ARE the required look, should realize that a person who does not come from a place or background where that is the norm is not necessarily one bit less frum than you are. They MAY even be MORE frum than you are.
ON THE OTHER HAND, those who DO come from places where jeans, etc. are NOT considered an inappropriate way of dressing for a frum person, must realize that for some frum Yidden, that way of dressing IS considered goyish, and that while it may be perfectly fine in SOME neighborhoods or cities (and have no negative connotation) dressing that way in a place like Boro Park (for example) will cause many people to view you (albeit incorrectly perhaps) as a less than truly frum Yid.
We definitely have some ideas about dress that are not always accurate. Example: In general, in N.Y. a knit kipa is associated with more modern orthodox and/or (the dreaded) Zionist chevra. But, go into Meah She’arim in Yerushalayim and you will see MANY wearing large white knit yarmalkas – and of course they are very far from modern orthodox OR Zionist!
Let’s try to not pre-judge each other or label each other negatively.