Paid search agencies manage the channel where money moves fastest in both directions: well-run accounts compound learning into efficiency, and neglected ones burn budget invisibly behind a monthly PDF. Comparing agencies is therefore mostly comparing controls: whether you hold the account, see the spend, and get outcomes reported in your economics. Craft differences are real, but they only matter inside a structure that lets you observe them.
The non-negotiable governance layer
Whatever the agency's talent, the structure comes first: ad accounts created and owned in YOUR name with the agency granted access, media billed at cost with management fees stated separately, direct platform login for you from day one, and change history visible so management activity is observable between reports. Google's ads policies govern what may run in the account; this governance governs whether you can ever audit what did. An agency that resists any of it is protecting either neglect or margin, and either answer ends the evaluation early, whatever the case studies promised.
The craft that separates managers, made observable
Inside a transparent account, quality is visible in specifics: campaign structures organized around your economics rather than template symmetry, search-term reviews that actually prune (check the negative lists' recency), conversion tracking wired to bookings, calls, and revenue rather than clicks, budget concentrated where cost per outcome earns it, brand terms defended deliberately, and a testing cadence for creative and landing pages with results written down. In vetting, ask candidates to narrate their last three optimizations on a real account and what each changed; managers with a practice answer instantly, and dashboards-only shops reach for the deck.
Fee models and the incentives they build
Percentage-of-spend fees scale with budget and quietly reward growing it; flat fees keep incentives cleaner but need scope definitions so service does not thin as spend grows; performance-fee hybrids sound aligned and invite attribution games around what counts as a conversion. No model is dishonest by itself; each needs its incentive named and countered in the contract: spend changes approved by you, outcome definitions fixed in writing, and reporting in cost per acquisition against your unit economics whatever the fee shape. Compare agencies on total cost against managed outcomes, and re-bid the engagement periodically; incumbency without audits is where paid search goes to decay.
Questions people ask about paid search agencies
What should paid search management cost?
Flat fees or spend percentages are both common; compare total management cost against outcomes managed, with media always billed at cost and fees stated separately. Opacity anywhere in that sentence is the red flag.
How fast should a new agency improve an account?
Structure, tracking, and pruning show inside the first month as visible changes; efficiency gains compound over the following weeks as data accrues. Judge month one on shipped changes, then cost per outcome thereafter.
Can I switch agencies without losing account history?
Yes, if the account is in your name: learning, history, and conversion data stay with you and the new manager inherits them. This is the biggest practical reason account ownership is non-negotiable.