The red cross means you can't wear it I believe because of either job, level or w/e. The dot in the upper right shows the main color of the clothing item. I don't know what green is for.... Maybe you can wear it but you are not a high enough level to get the best benefits from it? That's just speculation i remember when I was playing (over a year ago) you could wear items that were higher than your level but they would damage quicker and I read that now if you do it you wont spiritbond the item as quickly... hope that helps