On the last trip I meanly insisted Kim bought herself a local bikini. It's width was about the same as my outstreched palm it looked like it would fit an eight year old.
This time we shopped for one in Recife's poshest mall, packed like allthe others with bikini and sportswear shops.
Men's trunks are far more modest; Speedos with thick waist bands. The guidebooks tells you not to buy anything until you ascertain the local fashion, and as we approached Rio we saw more and more bermuda shorts being sold. The guides had been very clear about avoiding these if you were not to be an obvious gringo. (Winter skin tones should have been the other clue though we saw many Brazilians who were paler than we were.)
But Ipanema Beach had stuck with the Speedos and there were fewer dental floss bikinis.