Indeed they are, and it's big red flag when you see absurd bonus amounts and on absurd times (like at the end of IEO).
Whenever you see such IEO, ignore it unless you like to throw your money in drain (you should send me, if that's the case).
Bonuses are normally reduced as the token sales near its end. There is every reason to be alarmed when the opposite of the story is experienced, thus when the projects decides to give huge and weird bonuses at the end of the token sales. This could be that the token sales is not going well with the project and that have decided to increase the bonuses to lure investors.