Voting could be a Google Form with 3 options per row: “I don’t like it” (-1), “I’m indifferent” (±0), “I like it” (+1). Then you simply count the score.
• You can simply copy the options from the spreadsheet you got into the form, and each line will be a separate option.
↑ that’s a neat trick
• The user shouldn’t have to fill out all answers, as not answering and answering with indifferent is the same.