Lindsay Lohan -- The 'Dingy' Porno Movie Shoot

Lindsay Lohan rolled over to what she called a "dingy, shady, weird hotel" in the middle of Burbank, California last night -- but it wasn't on her personal time ... she was there to work.

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Lindsay --with a photog in tow -- hit this old Travelodge for an intentionally grimy photoshoot for her upcoming Linda Lovelace biopic.

Looks dirty.