Salah netted four times in Liverpool's 5-0 win over Watford on Saturday afternoon, and the attacker has now managed 28 Premier League goals for the Reds during the 2017-18 campaign.
No player in Europe's top five leagues has scored more than the 36 that Salah has managed in all competitions, meanwhile, and Robertson has lavished praise on his Liverpool teammate.
"He's easier to play with than against," Robertson told Sky Sports News. "That's for sure! In training, I think everyone dreads [coming up against him] but just now, I think he's one of the best in the business and nobody can deny that.
"I thought on Saturday he was unplayable. I thought he was unbelievable and I think that could have arguably have been his best game so far.
"To top it off with four goals was just ridiculous but it all comes from all of us working so hard. Mo gets in those positions all the time and just now he's putting everything away.
"He's not missing any chances and that's a good thing for us. Hopefully that continues because we've got a big run-in until the end of the season and if the front three can keep scoring the goals then hopefully that can be enough for us to reach our objectives."
Salah, 25, is reportedly a £200m summer transfer target for both Real Madrid and Barcelona.