After careful research, when you see a good ICO, you would know and there will be no doubt about it.
I have noticed that good ICOs also dump after listing, competing with crap ones that have no definite direction, but to cart away funds.
There are ways in which they can be protected and prevent unreasonable dump in price. Some of which are:

1. They should be managed by credible and trusted managers, managers that already have good reputation on the forum, else the trust might not be there.

2. KYC should be made mandatory for all bounty and airdrop participants in order to avoid multiple accounts. The kyc should be announced

3. Participants should be made to complete the remaining process of their registrations on the project's website, where IP can be detected. Multiple accounts can also be prevented this way.

4. Listing should be done on reliable and reputable exchange sites.

5. There should be regular and prompt communication with the community.

6. Projects should maintain and comply to their roadmaps and if there is amendment, the community should be made to know, with concrete reasons.

These are just few among so many other solutions, but if this few are integrated into the system, i believe dump can be minimized if not totally eliminated.