The only downside that I've come across is when you do something like: "%s %s" % blah If a bug causes `blah` to be a string (rather than a tuple or a list),

The only downside that I've come across is when you do something like: "%s %s" % blah If a bug causes `blah` to be a string (rather than a tuple or a list), it will attempt to expand the string, possibly giving a confusing error.