We have seen few scam ICOs.  I think during Bull phase when prices are rising every day; people are very much enthusiastic to invest in Alt coins by directly buying from the market and from the ICOs.  More and  more people then want to buy more and more coins because the price are rising day to day.
So as per my opinion the chances of cheating by scam ICOs are more while there is bull phase and the rising market.  So in a greed to become rich overnight, people sometimes buy such coins.  Even inexperienced people with greed; enter the market at those times; they become the easy target of such scams.
And during bear phase when the markets are falling; even good ICOs are finding it difficult to attract sufficient investors; so the chances of scam ICOs are low.
But I think we shall always be alert before investing; but more alert during rising market.

I am only 10 months old in this blockchain/crypto space. I have invested initially for the sake of taking quick profits, even saw 4x of my investment in jan 2018 but didn't book a profit and still HODLing onto my coins and tokens. I have started with $1000 investment and in the next subsequent dips in market, entered another $500-700. As of now my investment stands around $3500. And I'm now adding fiat of around $200 monthly.

I have learned about some really cool projects, they seems cool to me, I might be wrong though  
But what I have learned is that one should not HODL there entire investment in just similar altcoins. I have done a bit of my research and have divided the coins into different verticals/domains. If I have to add another $2-3k fiat in crypto, I would divide my portfolio into different verticals in crypto space.

Here are those verticals/domains:

1. Payment coins (BTC, LTC, NANO) - Both are targeting to be used as method of payment in the coming future. BTC would be first choice by returns from it will be low but steady. LTC could give 3-4x more gains than BTC but more risky than BTC.

2. Anonymous Coins (XMR, ZEC, DASH, PRIV) - Almost similar vertical as first except that these are basically have enhanced feature of making non-traceable anonymous transactions. Again I have written the coins as per the Lowest risk/returns to higher risk/returns as per my research. PRIV is the newest of all, only couple of months old. What I like most about them that they have not done any ICO to raise money and they are giving tokens for spreading news about them to there community members. More than 50% of tokens, around 11M of total 21M will be distributed for free.
Disclaimer: I hold around $700 worth of PRIV.

3. Platform Tokens (ETH, XLM, NEO, IOST, ICX) - Platforms that allowed dApps to be built on them, thereby increasing the blockchain applications and need of there tokens, as a result price will increase. ETH and NEO are most favorable and they are here for quite some time now. Developers of both have already proved themselves every now and then.

4. Exchange Coins/Tokens (BNB, KCS, HT, GVT) - These coins or tokens will be generally used inside there own exchange to reduce the trading fee by some percentage (generally 50%). As paying in other crypto yields more fee, people generally who trade in exchanges will be paying fees in respective exchange coin. Also these exchanges do a quarterly buy back and burn of there tokens, thereby significantly increasing there price.

5. Social network coins/tokens (STEEM, MITH, GTO) - These coins will be used within the social network platform built around them. Many users can earn by simply posting/liking/replying to articles/images.

6. Security tokens (POLY) - Currently only polymath allows security tokens to be built on there platforms. As per SEC chief all ICO's can be deemed as security in the coming future, there's huge opportunity for polymath. I know of another ICO (MOBU), which are on the same line as POLY is but they're still in ICO stage so can't say much about it.

7. Crypto loan (SALT, NEXO, MoneyToken) - This is a quite new vertical and an interesting one. People can deposit there fiat and take fiat as loan. It will help the people who needs fiat money for smaller amount of time but don't want to sell there crypto holdings. It could be the next big thing in crypto space.

Besides these there are several projects which are trying to replace traditional businesses using blockchain, like replacing online e-commerce, taxi-booking services, online advertisement etc. I have some projects to research on this vertical too, but don't know where to put them at. Maybe I'll put them under traditional business replacements projects (doesn't sounds cool though, suggest me if you can think of any good name).

These are the verticals as per my knowledge and research done yet, there could be many others which I have surely missed. I will update my post as and when i'll come across them.

Many say that ICO is unreliable. I do not support this point of view. The first - immediately visible in the project and the product and the team, you can cut off outsiders. The second is the probability that the token will fly 20 times higher than it will go down 5 times. As a result, I plan to invest in ICO.

at times like this what we have to do as a bounty so that an ico can run as we wish