Fake tans have stopped working! Heeeelp!

[EdithBouvierBeale]

I used to have skin that sucked up fake tan like an absorbent sponge. Now, I have developed immunity! I am your classic Scottish blue-white skinned, so need the glow to look human. I am very dark haired, so Morticia Adams is my alternative look.
The only tans that work, although mildly, are Fake Bake Flawless and Sublime Bronze. All other brands I have tried, and used successfully in the past, are now just very messy moisturisers.
Is there anything I can do to encourage the effectiveness of the products in my bathroom before I chuck them?

Make sure you're not putting them on after oily baths and whatnot.

Or maybe you've just stopped noticing the colour?

No oily baths. I cleanse and moisturise, then wait a while before applying the tan...the same way I have done for years.
Only two types give me a fan. The others, which used to work really well, now do nothing. Weird!

I wonder if the fecking EU have stuck their jackboots in and messed with the formulas, wouldn't be the first time.