I'd say that if there's no grease on the rotors, and if if looks like there's no grease slipping past the grease caps, you're probably ok. I have some grease looking stains on my rims and everything seems to be ok. The spots you see on the rims might be the result of brake dust being burned into the wheel finish. Apparently this can happen with brake dust reacts with water to form an acidic compound.

Alex

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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside