We audit a lot of analytics setups. The same five problems come up so consistently that we now check for them before looking at anything else.
1. Conversions that fire on page load
The single most common issue. A "form submission" event is placed on the thank-you page, which is reasonable — until you find the thank-you page is directly linkable, indexed by Google, and being reloaded by people who bookmarked it.
Worse is the variant where the event fires on the form page rather than after submission. Every visitor becomes a conversion, and the campaign optimising toward that event learns to find people who look at forms and leave.
Check: compare GA4 conversion counts against your CRM record count for the same period. If GA4 is meaningfully higher, this is usually why.
2. Internal traffic inflating everything
Your team visits the site constantly. Without IP filtering and internal traffic definitions, staff activity is mixed into every report — and for lower-traffic B2B sites it can be a substantial share of sessions.
Check: look at sessions by city and compare against where your offices are.
3. Cross-domain tracking not configured
If your checkout, booking tool or application form lives on a different domain, and cross-domain measurement isn't configured, the user is counted as a new session with a referral source of your own website. Your most valuable conversions get attributed to yourself.
Check: look for your own domain appearing in the referral traffic report. If it's there, this is broken.
4. No consent mode, in jurisdictions requiring it
Beyond the compliance exposure, this also means your data is either over-collecting where it shouldn't or silently dropping large volumes without modelling the gap.
5. Nobody wrote down what should be measured
The subtle one, and the root cause of the rest. Without a documented measurement plan — what events exist, what parameters they carry, what each one means — implementations drift. Developers add events with inconsistent names, marketers create conversions nobody else knows about, and within a year nobody can say confidently what any number means.
A measurement plan is a one-page document. It is the highest-leverage hour available in analytics work.
Fixing it
Work in order: document what should be measured, audit what actually is, fix the discrepancies, then validate against a source of truth outside GA4 — usually your CRM or payment processor. Only then start making budget decisions from the data.