I think the opposite. A good ICO usually has enough hype without any airdrops or bounties. And I don't think that airdrop can attract a lot of investors. Those who participate in airdrops, they usually don't have enough money for investing, as they're just looking for free tokens. So if ICO has an airdrop then it's not a good sign for me, and most likely I would skip such ICOs. But there's one exection, is when airdrop is held instead of a crowdsale, than I would definitely join such airdrops.