English Experts

[zumstein]

Em Português : Um passado duvidoso
Em Inglês ..… : A checkered past

Ex.:
A man with a checkered past.

[Nise]

A suspicious past

[Thomas]

Shady past

The Shady Past of Germany's Spyware
(http://www.spiegel.com.de)

[EugenioTM]

Also:

Doubtful past

Regards,

[Thomas]

I have heard "dubious past" but not "doubtful past". Can you give an example and cite the source? Thanks!

[EugenioTM]

Thomas, the source is freedictionary.com. Perharps "Dubious past" is more common.

4. Raising doubts as to legitimacy, honesty, or respectability; suspicious: the candidate's doubtful past.

[Thomas]

Thanks! I appreciate your time, Euegnio.