Thanks for the tip about isopropyl alcohol for stains. After a vase of lilies fell over onto our cream carpet (I know, we were asking for trouble), there was a stubborn yellow stain which was resistant to all cleaning solutions known to mankind. I'd tried everything: Vanish, stain remover, carpet cleaner - but a trip to Maplins for a £9.99 can of the stuff meant that I was spared the hassle of an insurance claim. I just sprayed it on and mopped it up with kitchen roll. Job done!
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Lily pollen stains on carpet -- yes! Isopropyl alcohol 99.9% really reaches the stains other cleaners cannot reach. Having tried soap and water, carpet cleaner, etc. I thought that the stains were simply made worse and permanent by my attempts.