It's clichéed, sure - but I'm biased.

[Wormholes]

Cliché is a noun: 'it's a cliché to say so'.

Clichéed is the adjective: 'it's a clichéed idea'.

Bias is a noun: 'the jury displayed bias'.

Biased (or biassed, if you prefer) is the adjective: 'the jury's decision was biased'.

I sometimes feel as though I'm the last person on earth who observes this distinction.

It looks wrong to write clichéed though doesnt it, since its clearly not an english word. Looks weird to put a D on the end to anglicise it yet keep the accent so it looks french.
Id have to say that idea was a bit of a cliché , rather than a clichéed idea

It's not clicheed as it's a french word. French doesn't add a D to past participles. It's cliché.

Oooh, all so gloriously pedantically pointless! I profoundly disagree with both of you. "Biased" is a past participle, not an adjective. And cliché is no more a French word than etiquette or coupon.