Une autre possibilité.

As they have defaulted on their duty to pay rent!

*

Commonly used and perhaps fairly PC while also pretty clear as to meaning

another idea...

I think this means that these are tenants who have not paid their rent, which rent is now "doubtful" to be recovered. I think it refers to tenants who are definitely in arrears and not just those about which there may be doubt or may seem dodgy.

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Note added at 13 hrs (2008-10-30 01:30:23 GMT)
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That is why this term appears in the section on managing overdue accounts.

Créances douteuses are doubtful loans in English, so you might as well extend the notion to tenants as well.
As with doubtful loans, there is no doubt that 'doubtful tenants' are indeed tenants. The doubt concerns whether they will pay the rent.
'High-risk' is probably too broad, 'defaulting' is probably too strong, 'unreliable' is too behavioural.

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Note added at 4 hrs (2008-10-29 16:53:08 GMT)
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The term pretty clearly means "tenants whose rent obligations have been or would be classified as doubtful receivables for accounting purposes".
It is not common in French (I get 126 gHits). That the analogous English construction is rarely seen is not an argument against using it, if it accurately captures the sense in the source language.

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Note added at 17 hrs (2008-10-30 05:48:07 GMT)
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Typical bank supervisor classification of loans (this one from HKMA):

"Pass: Loans for which borrowers are current in meeting commitments and for which the full repayment of interest and principal is not in doubt.

Special Mention: Loans with which borrowers are experiencing difficulties and which may threaten the authorized institution's position.

Substandard: Loans in which borrowers are displaying a definable weakness that is likely to jeopardise repayment.

Doubtful: Loans for which collection in full is improbable and the authorized institution expects to sustain a loss of principal and/or interest, taking into account the net realisable value of collateral.

Loss: Loans that are considered uncollectable after all collection options (such as the realisation of collateral or the institution of legal proceedings) have been exhausted."

Hello,

It means that the landlord is taking a risky on these tenants because there is a good change they won't pay their rent.

I sure wouldn't say "bad tenants" in a professional document. LOL. I've seen "risky tenants" used before in formal documents. I would not stray from saying "high-risk", though. That's not exactly what the French saying.