Would intentionally losing a raid and then beating it be wise?

I think you have to win to get the candy, at least that's how the announcement reads:

"Finally, when you're successful in a raid, you're guaranteed to receive a Rare Candy, and whether you win or lose, you'll earn 3,000 Stardust—six times the usual amount"

But it it may be worth using that tactic for the stardust if you can get 3K every time.

Niantic learned its lesson from the first special research quest. We used this trick to get through the "Fight in ten raids" task without buying lots of premium passes. "We" being many of the players that reached this task before Niantic closed this loophole.

Same scenario happened to me today. Lost the first attempt, got 4 candy on my 2nd attempt for 5 total

I think the answer is yes. There are two scenarios: You get a rare candy as a reward for winning or you don't. If you don't get a rare candy from winning then its the same and you gained nothing. However, if you were to gain a rare candy from winning then you will get a rare candy from your loss (since they promised at least one per raid). Then when you defeat the boss you get your rewards as normal. But this time they won't make the final check to make sure you got a rare candy (since you got one for losing). Since when you get your consolation rare candy it is at the end of all the rewards i am pretty sure it doesn't effect your normal rewards so they wont take any away instead they just check to make sure you got one in the end.

So yes, i think you can get more rare candy by using this trick, however the only places it is likely to pay off are tier 4/5 raids where you have to convince others of this.