I had the worst case of vaper's tongue 2 days ago. I had a bit of a cold (I figure that's what was responsible), but I couldn't taste any vape all day long. Couldn't tell the difference between grape and tobacco. Brutal.
Came back again the next day (thank god! I've heard of this going on for a week with some members).
Oddly enough, on a typical day, my vapes taste bad first thing in the morning, then taste better after breakfast & coffee, and tend to taste awesome in the late afternoon and early evening. Towards bed the vape starts to taste less and less (probably because I vape a lot once I'm home).
I've found drinking carbonated mineral water with a good dose of lemon juice clears the palette a bit.