"Search Page" located offsite

Is this an acceptable tactic?

[tlibson]

I have been offered a service by a commercial SEP outfit. They say that they create highly optimized pages in a subdirectory under their own domain and that, by working these pages, they will elevate my client's ranking on most search engines.

We do have SE problems to address but I'm afraid that this tactic will attract penalties. What's the deal?

[glengara]

Sounds like doorways designed to send you links/traffic, you'd be better off trying to address your own site's SE problems.

[tlibson]

Yes, "doorway" sound like the right description.
You're quite right about looking after the SE issues on the site but there is a complication regarding this service that I'd like not to get into here. However, it would help to have something fairly definitive to bring forward if this is definitely a BAD idea.

This "doorway" service would be fairly costly (many hundreds of dollars a month) but they do claim a "first page" guarantee for a certain number search engines. Is this credible? Is there a risk to my client?