To Clean or not to Clean, That is the Question

In terms of antiques, the general school of thought is that you don't clean antiques for fear of damaging the patina. In America (unlike the UK where they polish everything to a near new finish) an antique without patina is worth a fraction of the price. I don't disagree with that however...

Here's a pair of sterling overlaid candlesticks, the left one has the original patina, the right one I cleaned lightly with silver cream.

The one on the left looks good here, but the one on the right looks more like silver. Overall it's a toss-up between patina and presentation. But take a look at the same pair presented on a black background:

From the point of view of a dealer, it will be easier for me to sell a pair that looks like the one on the right (if I display them on a dark background). Is it going to devalue the candlesticks? I doubt it. Keep in mind that they're only $75; if they were were worth $750 I would think twice about it.

Here's another example, a 19th century reliquary in before and after states. It is rare and expensive enough that I paid to have this professionally restored. I think the results speaks for themselves; it's still authentic, but now you can actually see that the roof is gold plated (which I didn't even know before), which was hidden by corrosion (aka patina). In this case, I feel justified in asking for more money than I thought it was worth before.