Stay away from low value master node coin which could later scam investors have nothing to do with stay away from all master node project but due to the fact almost all master node coins go from grace to grass, the best way to advice a newbie is to stay away from master node project because newbies will not understand the features the look out for before choosing a master node base project.
Beginners should stay away from all the altcoins not just masternode coins because almost all of them are useless specifically the top 20 altcoins that are the most hyped up and most terrible coins created for pump and dumps.
I understand the hype base of the altcoin market make it hard for investors to understand the altcoin that performs genuinely well in the market but if we are talking about altcoin that included ETH which was another project that introduced new features to the crypto sphere (through the smart contract/dApp scheme) and I consider it not to be among the terrible coins you said.
ETH is not just bad it is the worst because it doesn't have the fundamental characteristics of a cryptocurrency and it was never capable of delivering any of the promises it made: decentralization, immutability, utility, security, cheapness,... none of them exist in ethereum!
You say "smart contracts" but have you ever seen even a single one that has any utility in real world? Of course not because the only usage of Ethereum and its smart contracts is to create useless tokens to raise funds and scam people. So it remains the most useless cryptocurrency of all times.
Compare that with bitcoin or even a useless altcoin such as Doge for example, they solve a problem in real world. People can use bitcoin to transfer money in a decentralized way that noone can censor. They tried calling ETH a currency when it was failing back in 2017 but since its fees shot up higher than bitcoin's that scheme also failed.