I'm interested to read this thread (and others on MN) about Folkestone having just been down for the first time to explore (and house hunt) yesterday.
Admittedly, the weather was drop-dead glorious, but I was super-impressed with what I saw - live blues in the rotunda on the Leas, the beautiful architecture of the west end, the creative quarter, a ska festival going on in the harbour, the relaunched harbour arm, plus some lovely, leafy, wide-avenued, suburban streets and parks.... I was really wowed.
I passed through what looked like the main shopping street - Sandgate Road? - which was bustling and perfectly presentable, if not particularly upmarket. I also drove past a big ugly shopping centre, and some ugly modern office buildings, but they seemed very easy to avoid if you wanted to.
What on earth am I missing? Why is it so ridiculously cheap? Why isn't everyone moving to Folkestone? It seems to have WAY more going for it than the other very affordable / less-than-80-mins-from-London coastal towns (we were also looking at Margate and Ramsgate).
I saw some grotty bits to the east of the creative quarter, but as a South East Londoner like the OP, I'm very used to grotty bits (albeit grotty bits in which it costs a million plus to buy a house). What's the catch??