MicrostockGroup

I assume its Front National if its extreme right in France...
Is  it this one Lisa?
http://www.marinelepen2012.fr/wp-content/uploads/2011/12/depliant_cmlp_chomage.pdf

Or if the pdf doesnt work, the one on top here?
http://www.francesoir.fr/actualite/politique/le-faux-sdf-de-marine-le-pen-172350.html

Thanks Artemis!  You are a wonderful sleuth! 

Very interesting article too.  Looks like she has been found out as using stock images.  In the days of google image searches and tin-eye it's probably a bad idea to use stock photos for political ads without stating that they are stock photos...

Glad they found it so convincing though

Wow, Lisa!  Your husband's fame just grows and grows!  At least they don't portray him as a supporter of the far-right.  I suppose that's some consolation.

Sorry your photo was misused in this way, Lisa. 
But isn't it great that it turned out to be a great way of discrediting the party.
Wow!

Rachel Maddow on MSNBC has regular segments exposing stock images (and recently, to her surprise, video) being used on political websites.

And then there's New Jersey Governor Chris Christie.  He had a political video ad that featured stock footage from Pond5.  How do I know it came from Pond5?  The Pond5 watermark makes several appearances.

https://www.youtube.com/watch?v=o-jgRUHNEMc&feature=player_embedded

Under EU legislation:
   

"Misleading and Comparative Advertising
What is misleading advertising?
Any advertising which, in any way, either in its wording or presentation:
    deceives or is likely to deceive the persons to whom it is addressed or whom it reaches."

The photo purported to be a French homeless man, at least by implication; so that's 'likely to decieve a person whom it reaches'.

http://ec.europa.eu/consumers/cons_int/safe_shop/mis_adv/index_en.htm

The trouble is with these things is that they're all subjective. The above is a moral opinion, which would have little legal traction.
However, there was a huge fuss recently about Sir David Attenborough's latest blockbuster, The Frozen Planet, when here were some complaints, blown out of all proportion, about a section of footage of a baby polar bear being born being shot in a Dutch wildlife park, not in the wild, even though details of the shooting were already on the FP website:
http://www.mirror.co.uk/celebs/tv/2011/12/13/frozen-planet-scandal-sir-david-attenborough-defends-fake-polar-bear-footage-115875-23631238
Obviously, it would have been totally unthinkable to disturb a birth in the wild, perhaps risking the mother or cub. The welfare of the animal MUST come first. Still, I'm sure it wouldn't be beyond the skills of a scriptwriter to have the voiceover saying 'like this footage' or something better, rather than imply it was taken wild.

As indeed could an unreleased editorial photo. Or a photo of an actual homeless person (moral opinion above noted).
'Posed by model' would have been the normal way to deal with this.

Kick him out and then you'll only have to worry about his nationality being wrong 

I think it is deceptive and therefore misuse.The image is being used as 'evidence' of the homeless issue. If it is such a big issue then they should have had no problem in gathering actual evidence.

Why would it be wrong to use a real homeless man? Provided he consented to be portrayed as such and was properly renumerated (just like any other model) what's the problem? A real homeless man might have been very grateful for the job and the food, clothes or whatever he chose to buy with the money. Not only that but he would be assisting the highlighting of an issue that affects him personally.

Probablt wouldn't be great either if the camera man was ripped apart and eaten 

I should have put "a tend to agree with the latter"; i dont have a problem with using a real homeless person either, as long as s/he was well informed and consented.
I don't think its misuse though; you can just as well say its being used to illustrate the homeless issue, rather than being 'evidence'; plus,  being the devil's advocate here: a picture of one real homeless person doesnt necesarily mean its a widespread issue in France, its doesnt add or substract from the truth, imho.