The friendly weather and less formal dress of summer combine to provide occasions when casual shoes combine well with suits. Shoes less formal than elastic sided slipons rarely look right with worsteds to my eye even now that the season is established, but the relatively simple caramel Cleverleys in the photo work with the mid-blue linen in the photo as well as several of its casual relatives and odd jackets generally. By the way, that is the very able Kealani of A Shine and Co. expertly plying her trade in the photo.
The implication of the preceeding of course is that slipons are rarely a good choice with suits in cool weather or the wet. Much of the rationale for that is practical. Low cut shoes with thin soles do little to keep feet warm or dry. But they also suffer aesthetically, since they are usually not scaled to complement the heavier suitings of fall (the relatively heavy construction of Alden's tassel loafers make them the principal exception in America but their make does not help their low cut so they still let the feet get wet). But back to summer.
I have written before that summer's bright light makes lighter colored clothing look better, and lighter clothing should have lighter colored shoes to accompany it. Leaving black shoes aside for the moment, as most men outside the City of London should do during the day anyway, and though there are periodic occasions where dark brown shoes can be effective, the real workhorses are in the range between chestnut and white inclusive. Caramel falls somewhere in the middle of that span, and it really is quite a tasty color for slipon shoes.