Twenty years after her debut in Hollywood, Sienna Miller remains one of the least sought-after celebrities out there. If that sounds harsh, consider the fact that Sienna herself admitted that it took her 20 years of acting to really embrace a lead role in part because of her reluctance to take the helm.

Clearly, the peaks and valleys in her career are the result of a combination of Sienna's feelings and the climate in Hollywood. And after a handful of scandals, Sienna was mostly sought-after because of the headlines she was making in her personal life, rather than what she could do on film.

Sienna Earned A Following For Her Relationships

There was the "love triangle" between her and Jude Law plus Daniel Craig, but that wasn't the worst of it. There was also the whole debacle where Jude stepped out on her with his nanny, which led to Miller's career really taking a backseat to all the rumors and speculation having to do with Jude.

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As happens sometimes, Sienna found her name attached to Jude's for years (and of course it's still that way now, sadly...). And as critical as it may seem, fans say there's a reason why Sienna Miller never became a Hollywood darling like her contemporaries.

Fans Say Sienna Miller Flies Under The Radar

Fans' perception is that Sienna Miller tends to fly under the radar because of her looks. It's not to say she's ugly by any means, but fans suggest that her nondescript looks didn't help her make waves in Hollywood.

Instead, they say, as much as they were "rooting for her" since her early acting days, Sienna "has a completely forgettable face." More than one fan pointed out that Sienna is beautiful, but that she's not recognizable the way that other stars are -- even if some of their features aren't as desirable.

It's kind of like the way Jennifer Grey allegedly lost roles after changing her face, in that looking like everyone else doesn't help an actress appear unique (duh).

Fans reason that it's this phenomenon that sort of tanked Sienna's career if the tabloids didn't do it for her back when her relationships were making headlines.

A variety of factors no doubt resulted in her being cast in "secondary" roles, noted Indie Wire, where she wasn't offered anything "substantial," but fans still think her looks are partly to blame.

And after 20 years of secondary roles, when Sienna Miller achieved a lead role, what was the gig? Portraying "Debra, a blue collar single mom still making the same mistakes she made as a teenager."

It doesn't sound like anything fantastic, but Sienna's range in the role cemented fans' love of her, even if she never peaked the way they hoped.

NEXT: What Kind Of Relationship Does Sienna Miller Have With Jude Law Now?