I really don't feel that a flavored beverage will effect the taste of the cigar. I actually feel it cleanses the pallet and refreshes the taste bud. If you eat one thing for so long it becomes dull over time.Any sugary, syrupy drink (or ANY flavored drink for that matter) will affect your taste of the cigar.
As many have mentioned, a full stomach absorbs the nictotine, and staying hydrated helps as well.
As long as the drink doesn't have a stronger after taste. I know with root beer it helps clean out the taste of the cigar and after a few seconds the taste of the root beer is gone.
I would say that EATING while smoking a cigar is a big no no as it WILL alter the taste of a cigar. Food particles will be in your mouth from chewing for 10 minutes at least.
Matter of preference though.:kissforeh