I've worn a Madras jacket in this two-street town, together with a white button-down, Levis and loafers (sockless).  I've worn a blue seersucker jacket and pink seersucker shorts - which may have been pushing it a little.  But I've only been abused once, from a car, back in 2009, when wearing a Brooksgate duffle coat and chinos. 
What I'd really like is a Monk-style Chinese hat. 
The Don Richards overcoat I once had caused a few stares.  It was well out of its time and place. 
I dearly loved Jeff G.  Think about him more or less every day.

I visited Russell Street at least twice in full regalia - Press lambswool jacket, Italian wool and cashmere coat, buttercup-coloured Brooks knitwear (not necessarily at the same time, you understand) to be met by Jeff in the kind of clothes Runninggeez  describes.  I was undergoing that learning experience that others - our Gibson, Jimmy Frost Mellor had had - of dressing in our Sunday best Ivy only to discover that Messrs. Simons, Strachan, Garet et al. were, to coin a phrase, 'stripped for action': JS in denim shirt or wearing a simple green Tootal scarf, Jeff in sweatshirt, shorts and white deck shoes, Kenny Lovegrove in navy pocket polo and jeans.
Back I went to the Ivy drawing board.

I see Ivy dressing as a paradox, a puzzle, an enigma.  'Look at me/Don't look at me/Look at me'.  Clothes send out signals, yes?  When my OS Madras cap turns up in the New Year, what do I team it with in the late spring and summer?  Something that simply does not catch the eye.  The cap thus becomes the 'one stand-out' item. 
I begin to wonder, though, if certain rules were laid down in the UK fairly late on which had only a partial relationship with Ivy in the US.  This as regards colour in particular.  I tend to abide by those rules now without giving it a massive amount of thought, but an older American poster might have a very different view.  But to do 'full-on USA' in England now takes a little thinking about.  As TRS has stated, Ivy is a 'mood' - thus capable of subtle alteration. 
The FB people are probably just attention-seekers.