大姦似忠

the most treacherous person appears the most guileless (idiom)

see 大夫[dai4 fu5]

big; large; great / older (than another person) / eldest (as in 大姐[da4 jie3]) / greatly; freely; fully / (dialect) father / (dialect) uncle (father's brother)

to fornicate / to defile / adultery / rape

see 似的[shi4 de5]

to seem / to appear / to resemble / similar / -like / pseudo- / (more) than

old variant of 似[si4]

loyal / devoted / honest