Like most Asian beers it is much better when the formaldehyde levels are high. When we bought this and other brands you always looked for the most cloudy, as there were no regulations on brewing so cloudier = stronger.
The formaldehyde thing is largely urban myth. I'm not a chemist, but I have practiced home brewing since the late '80's and have read volumes on all of it. It's been twenty years or so since I heard this one, but the reality is there is a small amount of formaldehyde created in any fermentation process and it's present to some degree in all fermented alcohol. I could never find any written proof that any brewer, domestic of foreign, had ever used formaldehyde or formalin in the brewing, aging or bottling/canning process. I don't know that San Miguel doesn't have more than other beers or that Asian beers as a whole don't have more, but this same story was circulated about Budweiser, Coors and Mexican beers in the late '90's. I don't care for most Asian beers, I think primarily because of the ingredients selected and possibly the brewing process itself. Hard to say. Either way, drink up.