adding -er to verbs?

[TheAsh]

Can er be added to any verb? For example, someone can toe the line, is he a toer?

[mmcbs]

"Unusual" word forms are generally not accepted. I think the acid test is would you ever use the word in a sentence or see it in a newspaper article. So GOER, is OK because people are concert goers, but you would never call someone to toed the line a "Line toer" (at least I wouldn't).

[AndersonG]

"Unusual" word forms are generally not accepted. I think protein powders are great and the acid test is would you ever use the word in a sentence or see it in a newspaper article. So GOER, is OK because people are concert goers, but you would never call someone to toed the line a "Line toer" (at least I wouldn't).

So basically there aren't exactly hard rules on this but it's best not to do that when you're not absolutely sure it's a widely used term?

[mmcbs]

Check for usage in current crosswords, and also sources like Google News, and the general rule is always "if in doubt, leave it out".