Contrary maybe to your experience, obtaining a good quality in web translation is not a game of Russian roulette. When selecting a translator/translation agency everyone is reasonably certain of a successful result. So leaving things to chance does not bode well for your final satisfaction. In fact, empirical data show that the editing time spent on any translation does not increase/decrease in linear proportions with the quality (or lack thereof) of the job done.

A good web translation job will save your time while a mediocre one will drastically increase the spent time proofreading/editing it, whatever the number of actual translation errors found in the document!

The mechanism is a simple one: as the proofreader/editor notices that translation errors are a bit too numerous, the possibility of further errors increases. Gradually, the editor rewrites larger and larger chunks of the copy.

In quite the opposite way, an editor correcting a generally well-written and technically accurate web translation will become less and less keen to superimpose an own idiosyncrasies on the translation job. Or in other terms, the editor tends to go by the rule "if it isn’t broke, don't fix it".

Based on this, how can you avoid the pitfalls of translator selection?

Give a specialized job to a specialized translator, ask about the translator's education and experience, small specialized translation businesses will often do a better job, the translator must team with an editor, share your own knowledge, ask for a glossary, allow your translator enough time to do a good job, cost may be an issue, but your time is often more costly.

Translating is NOT a machine job. The translator can make errors. The editor is here to pick up the pieces. Correct those awkward sentences. Straighten out too loose a style, adjust the terminology.

A good web translation editor will make a world of difference when the translation has been done right, but not 100% right. The difference can be measured in terms of hours of work saved, increased productivity and avoided aggravation.

Oftentimes, translators assume they know a subject because they looked up several times the translation of a technical term in a translation dictionary. Their knowledge of the word is limited to its translation; it’s not the real definition. A translation is not a definition but a meaning.