grammatical number - Should "riffraff", when used as a subject, be treated as a singular or a plural noun?

• riffraff (noun) people who are not respectable : people who have very low social status.

Merriam-Webster doesn't say anything about number. The Free Dictionary says it can sometimes function as a plural noun but doesn't explain when or how. Google books doesn't help much, there are several examples of it both as a singular and a plural noun.

1. In every period of transition this riffraff, which exists in every society, rises to the surface.




2. This riffraff are waiting for the cheap seats.

Looking at these two sentences, I can't find any structural difference that might lead one to use a singular or a plural verb. If one is writing a paper on social science and they want to use the word "riffraff", does it matter which verbal number is used?

Answer

I looked through the entry in the OED, and among all the senses of riff-raff applying to people I could not find a single example where the word had been used as the subject of a sentence. That is not to say that it couldn't be so used, but it provided no opportunity to determine whether it called for a singular or plural conjugation.

However one sense of riff-raff applies to worthless goods - trash. And there was an example of the subject in that category as follows:

2009 Eureka (Calif.) Times Standard (Nexis) 20 Feb. Now a days one
can easily tote their favorite records with them on a small
pocket-sized contraption and make no bother with the other riff-raff
that comes with the purchase of a CD.

As you can see it has been given a singular conjugation.

There was this one example, as regards people, where the word itself was given plural form:

2001 Ledger Disp. (Calif.) (Nexis) 4 Jan. 1 He conveniently left
out an entire gender, African and Native Americans, and most of the
rest who were considered riffraffs.

In conclusion I do not honestly think it matters in the least whether you make it singular or plural. Nobody is going to notice.