@Steve, you're more awesome than I care to say. Thanks for that incredibly generous offer, I already know where my freebet goes to;)
But it does not make sense why that would be anyway. Why would they?
Maybe they are monitoring the situation with local fiat bookies and than adjusting the odds to get maximum margin while still staying highly competitive. I know for a fact that some fiat bookies employ psychologist to better squeeze the players. His main job is to hand pick those few games labeled "super bets" - highly interesting games offered with no margin or very small margin with usual rule that you have to play at least 5 games on a ticket. It is very lucrative and competitive business so it is only natural that bookies resort to all sort of clever promotions, and odds tweaks.
My only physical experience with bookies were just low-level ones years before we ever had online access in the 1990s and these guys have extremely good memory, they almost have a mental picture of each target. Like you said, very psychological. Some people just love a bad bet, some like that 1.9 a lot more than 1.91.
And some like me, they know I'll take a sucker bet if they just bump it from 19/1 to 20/1.
I wonder if my online books even see that, I'll hover around some weird bet and only pick it when I see the value up a lot! I should point out, it HAS worked in my favour before!