I understand that one should stay well hydrated during a gout attack but i have also seen at many places that coffee is good for gout which can cause dehydration in excessive amount. so is coffee really good during gout or is it just a myth?

If you already have gout, drinking coffee may help for reducing acute flare up. Coffee reduces production of uric acid while helping to improve its excretion. A 2007 study, caffeine was found to have varied effects. One should not change their coffee habits for reducing or curing gout. Use reliable methods- avoid meat, shellfish and beer. Avoid adding sugar and high fat dairy cream.